AKI2ALL: Integrating AI and Blockchain for Circular Repurposing of Japan’s Akiyas—A Framework and Review

Abstract

Japan’s 8.5 million vacant homes (Akiyas) represent a paradox of scarcity amid surplus: while rural depopulation leaves properties abandoned, housing shortages and bureaucratic inefficiencies hinder their reuse. This study proposes AKI2ALL, an AI-blockchain framework designed to automate the circular repurposing of Akiyas into ten high-value community assets—guesthouses, co-working spaces, pop-up retail and logistics hubs, urban farming hubs, disaster relief housing, parking lots, elderly daycare centers, exhibition spaces, places for food and beverages, and company offices—through smart contracts and data-driven workflows. By integrating circular economy principles with decentralized technology, AKI2ALL streamlines property transitions, tax validation, and administrative processes, reducing operational costs while preserving embodied carbon in existing structures. Municipalities list properties, owners select uses, and AI optimizes assignments based on real-time demand. This work bridges gaps in digital construction governance, proving that automating trust and accountability can transform systemic inefficiencies into opportunities for community-led, low-carbon regeneration, highlighting its potential as a scalable model for global vacant property reuse.

1. Introduction

1.1. Background

Japan confronts a two-pronged challenge in the 21st century: the rapid exodus from rural areas not only erodes community vitality and cultural traditions but also leaves a surplus of vacant “Akiyas”—abandoned homes with potential for sustainable reuse. Some of the key factors driving this issue include urban migration fueled by better employment opportunities and modern infrastructure, as well as the financial burdens of maintaining older properties. Prohibitive upkeep costs, including property taxes and renovation fees, discourage ownership, particularly due to Japan’s complex inheritance tax system, where heirs may face taxes of up to 55% on inherited homes, making retention economically unfeasible [1,2,3,4,5].

Experts predict that by 2038, one-third of homes in Japan may be vacant [6]. Interestingly, even traditionally stigmatized “death-tainted” Akiyas (jiko bukken) are gaining appeal, offering 20% discounts that attract budget-conscious buyers as property prices soar nationwide [7]. On the other hand, foreign investors are increasingly seeking specialist advice to purchase and repurpose these properties, drawn by Japan’s weak yen and unique architectural opportunities [8]. In this sense, innovative adaptive reuse projects are emerging, converting Akiyas, e.g., into boutique hotels and cultural spaces that preserve traditional architecture while meeting modern hospitality needs [9]. In addition, community-led initiatives demonstrate particular promise, transforming abandoned houses into vibrant community hubs, showcasing the potential for circular urban regeneration [10].

Numerically, Japan has over 8.5 million Akiyas, representing 14% of its total housing inventory, though estimates suggest the actual figure could exceed 11 million. Among these, 4.4 million are available for rental, primarily in rural or peripheral regions, while 3.8 million remain unaccounted for, and 330,000 are actively listed for sale [11].

The proliferation of Akiyas exacerbates challenges in aging, depopulated areas. With 28.9% of Japan’s population aged 65+ in 2021—the rate projected to rise to 38.4% by 2065—rural regions face economic stagnation, particularly in agriculture, alongside a stagnant housing market. This creates a self-perpetuating cycle of disinvestment, stifling both private-sector involvement and public revitalization efforts. Additionally, the Akiya crisis threatens cultural heritage and local identity by jeopardizing historically significant structures, which are critical for cultural education and tourism. Simultaneously, neglected properties pose safety hazards, compounding societal risks. In this sense, Akiyas impose sustainability and development challenges since vacant properties in disinvested areas drag down local economies [12,13,14,15].

Heirs often inherit burdensome tax liabilities—up to 55% of a property’s value—without viable means to retain or repurpose the assets [5]. Besides, communities suffer from economic stagnation, cultural erosion, and heightened risks of crime or fire [12,13,14].

The Japanese government has acknowledged the urgency of the Akiya crisis and its far-reaching consequences for national progress. To combat rural depopulation and revitalize countryside communities, it has launched a range of initiatives, including financial incentives such as grants for renovating vacant homes and relocation subsidies [16,17,18]. Despite these imperatives, current policies fall short. The Japanese government has deployed measures like the 2015 Vacant House Countermeasures Act and subsidies for rural relocation. Local “Akiya Banks” (online databases of free or cheap homes) and one-time grants (e.g., ~¥600,000 per family for moving to the countryside) aim to stimulate reuse. However, these efforts have had limited impact. Public registries often suffer from outdated listings (opacity in transactions) and low participation, while lump-sum subsidies offer no ongoing incentives to renovate or occupy a home. In practice, renovation projects frequently stall due to unclear responsibilities or disputes over workmanship. In sum, there is a lack of scalable, transparent, automated mechanisms to mobilize Akiya as community assets [19,20].

It is important to note that while AKI2ALL and Akiya Banks both address vacant properties, they serve fundamentally different purposes. Akiya Banks are static directories—essentially bulletin boards listing properties without automated processing, demand matching, or regulatory integration. In contrast, AKI2ALL operates as a dynamic, AI and blockchain-powered platform that automates the entire repurposing lifecycle, including real-time use-case allocation, tax/permit processing, and contract execution.

1.2. Motivation

The inspiration for this work came from following up a short documentary by the Japanese TV station “NHK World” that explored innovative uses of Japan’s vacant homes, as highlighted in the “Japanology Plus” broadcast on 25 April 2024 [21]; this interview depicted how both private companies and government initiatives are exploring relaxing laws and regulations, and the potential deployment as emergency housing during natural disasters.

Despite policy efforts like Akiya Banks and subsidies, systemic inefficiencies persist. First, existing solutions lack dynamic mechanisms to match vacant properties with real-time community needs, relying on static registries [22,23]. Second, bureaucratic delays in tax adjustments and permit approvals discourage reuse [19,20]. Third, current programs rarely integrate circular economy principles, often favoring demolition over adaptive reuse [1,24]. AKI2ALL addresses these gaps by proposing a unified digital platform that automates workflows, ensuring transparency and agility in repurposing.

Japan’s efforts to revitalize rural areas have so far been piecemeal and insufficient. Well-known initiatives like municipal Akiya Banks (databases of vacant homes) and one-off relocation subsidies have not scaled up effectively. As Herrador et al. observe, existing solutions—such as Akiya Banks and relocation subsidies—have failed to scale due to three systemic gaps: opacity in property transactions, incentive misalignment, and fragmented accountability [22]. In practice, many Akiya Banks list only a handful of properties, and buyers still face real-estate agents, renovation costs, and often must live in the home for decades. These measures have led to limited follow-through; without supporting infrastructure or sustained incentives, rural dwellers and newcomers remain disconnected, and large stockpiles of empty homes persist [23]. In contrast, vacant houses represent a latent circular resource that current programs fail to harness. From a material-stock perspective, they still contain reusable. Wuyts et al. emphasize that vacant houses represent material stock and still have potential in the circular economy, yet Japan’s policies rarely integrate circular reuse (demolition and new builds remain cheaper than renovation in many regions) [1].

1.3. Goals

To address the previous gaps, we propose AKI2ALL, an AI and blockchain-powered framework for circular repurposing of vacant homes. AKI2ALL provides a digital marketplace and workflow management system where Akiya owners, municipalities, and end-users interact via smart contracts, ensuring an agile repurpose of Akiyas automated in the public administration and validated through blockchain (Figure 1).

The AKI2ALL lifecycle (Figure 1) begins when Akiya owners or Akiya Banks list properties on the platform based on real-time demand, zoning laws, and circularity potential. Municipalities then automatically validate ownership and tax status via blockchain, while smart contracts instantly adjust taxation/permits upon approval. Finally, repurposed properties are listed on a transparent marketplace where end-users (entrepreneurs, community groups) discover and utilize them via AI-matched smart contracts—completing the cycle from vacancy to community value. Using blockchain, AKI2ALL creates immutable records of each Akiya repurpose, automating trust among owners, renovators, and funders. AKI2ALL aims to restructure vacated housing from an underutilized property into a community asset [24], turning the Akiya crisis into an opportunity for circular revitalization. In this way, AKI2ALL automates trust and accountability in Akiya repurposing, ensuring that occupancy rights or subsidies are activated only when the utility shift is validated. The result is a transparent, streamlined system where municipalities list available Akiyas, owners, and financials in Akiya Banks can effortlessly select or propose new uses.

AI was selected in this study because it enables dynamic, real-time matching between vacant properties and community needs, a critical capability missing from existing static registries like Akiya Banks. By integrating AI into AKI2ALL, the framework can forecast demand, automate decision-making, and optimize the reuse of each property in alignment with zoning laws and circular economy principles. This agility allows repurposing decisions that once required weeks of manual review to be completed in hours, significantly reducing delays. Combined with blockchain, which ensures transparency, trust, and automated compliance, AI may make AKI2ALL useful for addressing Japan’s vacant housing crisis into a system of community-driven, low-carbon redevelopment.

The contribution of this work advances the state of the art in circular reuse by integrating the construction sector with previously disconnected domains: (1) AI-driven demand-property matching for dynamic repurposing (unlike static Akiya Banks), and (2) blockchain-automated municipal workflows (tax/permits) that eliminate manual delays plaguing existing systems. This work is organized into (1) Introduction (Section 1), (2) Methodology (Section 2), (3) Literature Review (Section 3), (4) Design of AKI2ALL (Section 4), (5) Discussion (Section 5), and (6) Conclusions (Section 6). The use cases are summarized in

Table 1. Summary of the 10 AKI2ALL case studies developed from literature and expert input.

Use Case	Sectors	User Type	Circular Economy Indicators
1. Guesthouse	Tourism, Hospitality	Foreign entrepreneurs and local hosts	Percentage of recycled materials, energy-saving targets, local labor %, cultural heritage elements
2. Co-working Space	Remote Work, Innovation	Tech startups (local/foreign), digital nomads	Modular furniture reuse, building-energy efficiency, broadband infrastructure reuse
3. Pop-up Retail and Logistics Hub	Commerce, Craft, Tourism, e-Commerce	Local artisans, visiting customers, shipping companies	Reusable market stalls, zero-waste packaging, local-supply emphasis
4. Urban Farming Hub	Agriculture, Agritourism	Local farmers, community volunteers	Organic waste composting rate, rainwater reuse, eco-friendly soil amendments
5. Disaster Relief Housing	Emergency Response	Government, NGOs, displaced residents	Modular housing reuse, quick-construction kits, post-use community functions
6. Parking Lot	Transportation, Infrastructure	Local residents, commuters	EV charging stations, rainwater collection, shared vehicle programs
7. Elderly Daycare Center	Social Services	Local government, senior-care organizations	Accessible design upgrades, indoor-outdoor greening, renewable heating/cooling
8. Exhibition Space	Small-Scale Manufacturing	Craftspeople, tech startups	Recycled tool/material usage, on-site recycling systems, maker-space sharing rate
9. Food and Beverages	Convenience Store, Cafe, Restaurant, Tourism	Entrepreneurs, visiting customers	Energy efficient equipment, reduced food waste, composting, food donation programs, local and seasonal-supply emphasis
10. Company Office	Green Technologies e.g., Renewables Production	Local energy co-op, tech firms	Solar/Biogas installation area, % renewables generated, grid feed-in rate

, then described in Section 4, and discussed in Section 5.

2. Methodology

This study followed a structured multi-phase methodology to design, simulate, and evaluate the AKI2ALL framework for the circular repurposing of Japan’s vacant homes. The process comprised three key stages: literature review, use-case definition, stakeholder validation, and simulation-based feasibility testing.

First, we conducted a systematic literature review following PRISMA guidelines to examine Akiya reuse, circular construction, and AI-blockchain applications. Our search strategy employed the following string in Scopus, JSTOR and Web of Science: (‘vacant hous*’ OR ‘akiya’ OR ‘abandoned propert*’) AND (‘artificial intelligence’ OR ‘AI’ OR ‘machine learning’) AND (‘blockchain’ OR ‘smart contract*’ OR ‘decentralized governance’) AND (‘circular economy’ OR ‘adaptive reuse’ OR ‘urban regeneration’). Initial screening of 422 records applied inclusion criteria focusing on English and Japanese journal articles, conference papers, government reports in urban studies, construction engineering, computer science, and environmental science, obtaining 94 references in total (Figure 2).

Second, we defined ten representative use cases for Akiya reuse, based on recurring themes in the literature and government initiatives. Each use case represents a real-world scenario (e.g., guesthouse, elderly daycare center, or urban farm) and includes a unique configuration of stakeholders, spatial context, and circular economy outcomes.

Third, the use cases were refined through structured consultation with eight domain experts (two urban planners, two civil engineers, and four computer scientists) affiliated with the University of Jaén who previously collaborated with the main author in the “Smart City Jaen” project. Experts were invited via email to participate, and all agreed (8/8). They evaluated each use case through structured online Google forms, providing feedback on technical feasibility, social acceptance, and regulatory alignment over three weeks. Conflicting perspectives were resolved through iterative group discussions via email. This input was incorporated into the final designs through two review rounds, ensuring practical alignment with circular economy principles.

The entire process is summarized in the following flowchart (Figure 3).

3. Literature Review

3.1. Defining Vacant Properties in the Context of Circular Reuse

There is currently no universally accepted definition of vacant property, and interpretations vary across academic, policy, and practical domains. In academic literature, vacancy is often defined temporarily as properties left unoccupied for six months or longer [25,26,27]—and interpreted through lenses of urban blight, structural decline, or social disinvestment [28,29,30]. Scholars distinguish between intentional vacancy (e.g., properties held for speculation or secondary use) and unintentional vacancy (e.g., due to the demographic decline, inheritance complications, or lack of market demand) [31,32,33].

By contrast, the Japanese government adopts a more formalized classification. According to the Ministry of Land, Infrastructure, Transport and Tourism (MLIT), a property is classified as Akiya when it has remained unoccupied for over one year and is unlikely to be used by its owner in the foreseeable future [34]. The MLIT further categorizes Akiya into four types: (1) for sale, (2) for rent, (3) for secondary/vacation use, and (4) other vacant homes, which are typically long-term unutilized assets with no clear use intention.

The divergent definitions serve different purposes: academic definitions illuminate socio-economic dynamics and inform theories of urban shrinkage, while governmental classifications enable administrative action and policy targeting. For AKI2ALL, which spans both residential and non-residential typologies, the broader term vacant properties better reflects the platform’s intent to include multiple building types in circular repurposing workflows, from houses to commercial structures and community facilities.

In addressing Japan’s growing Akiya crisis, it is essential to clarify what constitutes a “vacant house” or, more broadly, a “vacant property.” The term Akiya (空き家), commonly used in Japanese policy and media, traditionally refers to detached residential houses that are unoccupied and often neglected. However, for this study and the AKI2ALL framework, the term “vacant properties” is deliberately used in a broader sense limited solely to residential houses but inclusive of various underutilized or abandoned built assets, including former shops, schools, offices, and public buildings, which possess repurposing potential. This inclusive framing aligns with the circular economy ethos underpinning the AKI2ALL framework—prioritizing reuse and functional transformation of any underutilized built asset, regardless of its original purpose, thereby expanding the opportunity set for revitalization, especially in rural and aging areas.

3.2. Akiya Crisis and Policy Gaps in Japan

Urban shrinkage, marked by population decline and a rise in vacant housing, has emerged as a critical challenge in numerous developed nations [35,36,37]. Japan exemplifies this trend, grappling with sustained population loss and a pervasive issue of unoccupied dwellings. According to the 2018 Housing and Land Survey, Japan has roughly 8.49 million vacant homes, accounting for 13.6% of the nation’s total housing stock [38]. Projections suggest that by 2033, the vacancy rate could escalate to nearly 30%, implying that one in every three houses may be abandoned [39,40,41].

Poorly maintained vacant properties, often due to lack of owner engagement, contribute to various neighborhood concerns. These include deteriorating streetscapes, structural collapse hazards, arson, pest infestations, illegal waste dumping, and criminal activity [42,43,44,45]. Furthermore, such properties can depress adjacent land values and deter potential investors or tenants, exacerbating urban decline with a shrinking population [46,47]. The presence of vacant homes may also erode community cohesion and perceived safety, adversely affecting residents’ well-being, thus, addressing this issue is therefore imperative.

To mitigate the problem, the Japanese government introduced in 2015 the Act on Special Measures to Promote Vacant House Countermeasures, providing a regulatory framework for local governments. This was supplemented in 2016 by the Vacant House Countermeasures Comprehensive Support Project for facilitating policy implementation [48,49].

While these initiatives represent foundational steps toward preventing and reducing housing vacancies, they often fail to harness the full potential of vacant properties as community resources. Among existing strategies, adaptive reuse stands out as a sustainable approach aligned with circular economy principles [50].

3.3. The Importance of Adaptive Reuse in Japan for a Circular Economy

Adaptive reuse of Japan’s vacant homes (Akiyas) presents a sustainable solution to urban decline, offering environmental, social, and economic benefits. Environmentally, it reduces waste and carbon emissions by repurposing existing structures instead of demolishing them, aligning with circular economy principles [51,52,53]. This approach is often more cost-effective than new construction, particularly in regions with high demolition costs [54].

The Akiya crisis is exacerbated by systemic inefficiencies in Japan’s property market, including rapid depreciation of housing (treated as valueless after 25–30 years), disincentives for renovation due to financing biases favoring new construction, and complex inheritance norms that leave properties unregistered or abandoned [55]. Urban sprawl further dilutes demand for existing homes, while absentee owners—often deterred by high demolition costs or sentimental attachments—resist relinquishing properties, perpetuating underuse [56]. These institutional and sociocultural barriers highlight the need for reforms to streamline ownership transfers and incentivize adaptive reuse, as current measures like Akiya Banks struggle to bridge mismatches between supply (owners prioritizing sales) and demand (migrants seeking rentals) [57].

Socially, adaptive reuse revitalizes neighborhoods by converting abandoned properties into functional spaces, enhancing safety and community cohesion [58]. It also preserves cultural heritage, as seen in the transformation of traditional homes into tourist attractions or local businesses [59]. For aging populations, repurposed Akiyas can support well-being by fostering social interaction and accessibility [60,61].

In Japan, adaptive reuse is gaining traction through government subsidies, Akiya Banks, and private initiatives [62]. However, challenges remain, including ambiguous terminology and localized studies that lack a national perspective [63].

3.4. AI/Blockchain for Agile, Trustworthy Asset Management in the Built Environment

Innovative digital technologies are increasingly seen as tools to reimagine Japan’s built environment, though they lag behind global leaders in AI-specific construction studies [59]. Nonetheless, Japan is pursuing “Society 5.0” and smart city initiatives encouraging AI, IoT, and blockchain for urban infrastructure. Studies of global practice suggest AI and blockchain can optimize design, project management, and supply chains (e.g., via building information modeling and smart contracts). Surveys of Japanese stakeholders identify digital solutions for buildings as material banks as a top circular innovation in construction to keep reusing buildings as a circular material flow, with the potential to stimulate Akiya renovations [64,65,66,67,68]. Herrador et al. (2025) demonstrate that combining AI and blockchain technologies can dramatically streamline construction and asset management processes, enhancing agility and trust in tasks like permitting, refurbishment verification, and property tax compliance [22].

AI contributes by automating and accelerating many building-management tasks. Likewise, surveys of AI-for-construction note that AI-managed analytics can accelerate project planning, improve safety, and cut overruns. In the context of vacant-house reuse, AI-driven processes make asset management more agile—decisions that once took weeks of documentation can occur in hours, with algorithms handling routine checks and optimizations (freeing human staff for higher-level oversight) [69,70].

Blockchain brings complementary benefits of trust, transparency, and data integrity. By storing critical asset and transaction records on a decentralized ledger, blockchain ensures an immutable audit trail that all parties (municipalities, owners, and Akiya banks) can share. As Perera et al. note, maintaining records on blockchain enables tracking the history of assets, providing trustworthy proof of ownership, reducing transaction times and costs, and minimizing fraudulent behavior to address trust issues across construction supply chains. In practice, tax authorities or new occupants can instantly verify the update Akiya purpose without needing paper records or intermediary checks, thus, disputes over property titles or renovation claims drop dramatically [71,72,73].

Moreover, in an Akiya-repurpose context, one could similarly automate permit releases or tax rebates once AI confirms that key retrofit steps are done when repurposing an Akiya. This replaces slow, paper-heavy approvals by instantly enforcing rules, minimizing human delay, reducing bureaucratic load, and streamlining property leases for business owners and landlords as a novel real estate innovation [74,75,76].

4. Design of the AKI2ALL Framework

The AKI2ALL framework operates through a five-step, AI-blockchain-integrated workflow that enables the circular repurposing of vacant properties in Japan. The process ensures transparency, regulatory compliance, and agility in adapting buildings to new community uses. Below, we detail the framework’s lifecycle, aligning it with the step-by-step process illustrated in Figure 4.

Step 1: Property Listing Akiya owners or local Akiya Banks begin by listing properties on the AKI2ALL platform, uploading structural data, ownership records, location, and photographs. This initiates the digitization of each property within the system and prepares it for automated matching and validation.

Step 2: AI-Based Use Matching an AI engine analyzes current community needs, zoning regulations, and building characteristics to suggest the most suitable repurposing option (e.g., guesthouse, urban farm, co-working hub). This step replaces static listings with dynamic recommendations and eliminates the need for manual assessment or classification.

Step 3: Blockchain Validation Municipal authorities access the blockchain-based records to confirm ownership, tax status, and legal compliance. Once validated, smart contracts automatically adjust tax rates, generate permits, and register the new intended use—ensuring legality and reducing bureaucratic delays.

Step 4: Smart Contract Execution Upon validation, the platform automatically executes the smart contract, encoding the property’s new use, any applicable subsidies or grants, and operational conditions. This replaces paper-heavy workflows with legally binding, tamper-proof records.

Step 5: Marketplace and Activation Finally, repurposed properties are published in a public marketplace, where community groups, entrepreneurs, or public entities can lease or acquire them under transparent conditions. If needs evolve, the system allows properties to re-enter the loop at Step 1 for further adaptive reuse, thereby preserving the circular value of the built environment.

The AI component employs supervised learning models (e.g., random forests or gradient-boosted decision trees) trained on historical property-repurposing data, zoning laws, and community demand indicators to optimize use-case matching. For blockchain implementation, AKI2ALL uses a permissioned ledger (e.g., Hyperledger Fabric) with smart contracts encoded in Solidity, ensuring only verified stakeholders (owners, municipalities) can validate transactions. Moreover, the system architecture follows a modular microservices design, allowing municipalities to customize AI weightings (e.g., prioritizing elderly care in aging regions) while maintaining core blockchain verification standards. While specific model parameters would depend on local implementation, this design ensures scalability across Japan’s diverse regions.

Table 2. Smart contract example.

Section	Field	Description
Admin Info	Owner/Representative ID	Unique identifier (e.g., wallet address) of Akiya owner or Akiya Bank agent.
	Contact Email	Primary contact for notifications.
	Digital Signature	Cryptographic proof of consent.
Akiya Data	Property ID	Municipal registry ID or geolocation tag.
	Structural Condition	Options: Good, Needs Repair, Unstable.
	Size (m2)	Floor area and plot dimensions.
	Historical Value	Is the property culturally significant? (/)
	Photos/Documents	Links to structural reports, images (stored on decentralized storage), and property deeds in PDF.
Municipality Data	Zoning Code	Pre-filled from the municipal database (e.g., Residential, Commercial).
	Tax Status	Paid, Pending, Exempt (validated via blockchain).
	Permit Requirements	Auto-suggested based on repurpose category (e.g., Fire Safety, Accessibility).
Repurpose Proposal	Intended Use	Selected from the 10 categories (Table 1).
	Funding Request	Grant/subsidy amount (if applicable).
Municipal Approval	Predefined Use Category	Approved repurpose category based on zoning laws (e.g., Urban Farming Hub).
	Compliance Score	Verified % material reuse and energy efficiency per municipal standards.
Smart Contract	Terms Hash	Immutable record of ownership/permit approvals on blockchain digitally signed.

illustrates AKI2ALL’s blockchain-native smart contract architecture, designed to automate transactions while ensuring trust between owners and municipalities.

The following Section 4.1, Section 4.2, Section 4.3, Section 4.4, Section 4.5, Section 4.6, Section 4.7, Section 4.8, Section 4.9, and Section 4.10 describe each hypothetical scenario’s configuration (users, region, intended outcome), explain how AKI2ALL’s features, and highlight which circular economy dimensions (material reuse, resource optimization, social reuse, etc.) are addressed.

The AI component of AKI2ALL plays a central role in addressing static property listings into a dynamic, data-driven repurposing system. Rather than relying on user browsing or fixed listings as in conventional Akiya Banks, the framework applies AI algorithms to optimize the match between vacant properties and evolving community needs. These algorithms consider variables such as building typology, structural condition, location, surrounding demographics, and regional demand trends—enabling automated use-case recommendations (e.g., guesthouse, daycare center, or co-working hub) compliant with local zoning and circular economy criteria. This approach ensures that repurposing is not only more agile and context-aware but also reduces manual planning overhead, supporting municipalities in areas with limited administrative resources.

4.1. Guesthouse

In this scenario, a vacant rural house (for example, an old inn or barn) is renovated into a community-run guesthouse to boost local tourism and income. The configuration involves local entrepreneurs, volunteers, and possibly municipal support in a mountain village; the intended outcome is eco-friendly lodging with cultural value. This use case embodies circular economy principles by emphasizing property reuse, resource optimization (energy-efficient systems), and social reuse (reviving heritage architecture and involving local craftsmen).

4.2. Co-Working Space

A former rural office or school building is reconfigured as a co-working hub for local entrepreneurs, freelancers, and small businesses to revitalize a town center. Users include start-ups and remote workers; the intended outcome is a collaborative workspace that fosters innovation and economic growth. This use case highlights circular economy aspects through material reuse (renovating an existing structure), resource optimization (sharing office equipment and reducing energy use per person), and social reuse (co-learning and networking to leverage community knowledge).

4.3. Pop-Up Retail and Logistics Hub

This use case envisions an underutilized public square or series of vacant storefronts hosting temporary pop-up markets for local artisans, farmers, and food vendors. Stakeholders include market organizers, vendors, and consumers; the goal is to stimulate the local economy and social interaction. This case advances circular economy principles through material reuse (repurposing public space and temporary structures), waste reduction (incentivizing recycling and food redistribution), and social reuse (reviving public areas for shared community value).

4.4. Urban Farming Hub

An empty lot or rooftop in a suburban town is transformed into an urban farming hub to supply local produce and engage citizens. Participants include community gardeners and urban farmers; the outcome is year-round food production and green space activation. The case embodies circular economy dimensions through resource optimization (closed-loop water and waste reuse), material reuse (composting organic matter), and social reuse (sharing gardening knowledge and healthy food within the community).

4.5. Disaster Relief Housing

Modular units (such as shipping containers or prefabricated shelters) are rapidly deployed to provide emergency housing after a natural disaster. Users include displaced families, NGOs, and local volunteers; the intended outcome is safe, reliable temporary accommodation. This scenario links to a circular economy by reusing materials (repurposing containers or debris), optimizing resources (efficiently matching housing to need), and leveraging social reuse (mobilizing community support networks and skills during recovery).

4.6. Parking Lot

In this scenario, vacant land or structurally unsound Akiyas in high-demand urban zones are converted into managed parking facilities to alleviate congestion and generate municipal revenue. The configuration involves local governments, private parking operators, and community associations in areas with acute parking shortages; the intended outcome is optimized land use with integrated smart mobility features. This use case embodies circular economy principles through space-sharing algorithms (dynamically allocating spots for residents, commuters, and commercial vehicles), EV charging infrastructure powered by renewable energy, and rainwater collection systems to reduce runoff. By repurposing underutilized lots instead of new construction, the model preserves urban land resources while creating adaptable infrastructure that can later transition to other uses.

4.7. Elderly Daycare Center

Underused housing units in a village are renovated into a shared living community for elderly residents and caregivers. Users include seniors, family members, and volunteer helpers; the intended outcome is affordable co-living with mutual support. This case highlights circular economy aspects such as material reuse (refurbishing existing homes), resource optimization (e.g., shared kitchen and utilities reducing per-capita consumption), and social reuse (building intergenerational support networks and sharing caregiving skills).

4.8. Exhibition Space

A closed-down factory or school lab is converted into a communal workshop and startup incubator supporting local entrepreneurs and artisans. Users include makers, mentors, and students; the outcome is local innovation, skills development, and job creation. This use case enables circular economy by promoting material reuse (using scrap materials and shared tools), resource optimization (coordinating tool usage to reduce idle time), and knowledge reuse (based on skills and encouraging collaborative learning).

4.9. Food and Beverages

A vacant house that has high historical value is adapted to serve the new function of the food and beverages category. The new functions can be various such as cafes, convenience stores, restaurants, and bars. Entrepreneurs and visitors are the main stakeholders that provide a place to rest and relax in high historical settings. This case contributes circularity through energy-efficient equipment, reducing food waste, composting, food donation programs, and local seasonal-supply emphasis.

4.10. Company Office

Preferably a green one; it is proposed a disused site or building be turned into a small-scale renewable energy lab or microgrid pilot (e.g., solar panels, wind turbine, battery storage) to provide clean power and training opportunities. Stakeholders include researchers, a local utility, and community members; the outcome is sustainable energy production and technology dissemination. This use case promotes circularity through resource optimization (maximizing renewable output and recycling batteries), material reuse (refurbishing older components), and knowledge reuse (training local technicians on sustainable technology).

4.11. The Blockchain Component

The AKI2ALL framework integrates blockchain technology as its foundational layer to ensure trust, transparency, and automation across all ten use cases. The blockchain serves as an immutable registry for Akiya listings, ownership records, and repurposing agreements. Municipalities, Akiya banks, and homeowners upload property details—including structural conditions, zoning permissions, and historical data—to a shared ledger. Smart contracts then automate administrative workflows, such as title transfers, tax validations, and incentive disbursements, eliminating bureaucratic delays.

By anchoring AKI2ALL in blockchain, the framework achieves (1) agility, since administrative processes (zoning approvals, subsidy distribution) execute in minutes rather than months, (2) trust, due to parties accessing a single source of truth for property status, payments, and obligations, and (3) scalability, given that modular smart contract templates allow rapid adaptation to new use cases or regions.

Moreover, the framework’s permissioned blockchain architecture specifically accommodates Japan’s data privacy laws, allowing selective transparency where municipal regulators access full transaction histories while individual users maintain control over personal data. This balance between regulatory oversight and privacy protection represents a significant advancement over conventional property databases, which typically suffer from either excessive bureaucracy or inadequate verification mechanisms.

4.12. Advantages and Limitations Toward Revitalization and Circularity

Across these ten use cases, AKI2ALL’s common strengths include a unified AI-blockchain core that brings data-driven decision-making, transparency, and automated accountability to diverse community projects. Many scenarios naturally align with circular economy goals by reusing existing buildings and resources with a wide number of new purposes. Feasibility varies by context: urban-based cases like co-working hubs or energy labs can leverage existing infrastructure with relatively low overhead, whereas high-impact cases like disaster housing and elder care require significant coordination and investment. Stakeholder complexity also differs: some cases involve only grassroots community groups, while others require multi-party collaboration (e.g., local governments, NGOs, private partners). Each scenario contributes differently to rural revitalization (through tourism, local jobs, new services, or energy resilience), although success often depends on local demand and supportive policies.

AI-automated smart contracts optimize the verification and payouts, reducing administrative overhead. Transparent cost accounting and immutable records build stakeholder trust. By design, the system enhances circularity: every use case encourages local material or energy reuse and shared resource use, aligning with rural sustainability objectives.

Regarding challenges and limitations, these applications depend on reliable digital infrastructure and sufficient tech literacy, which can be limited in rural areas. Certain scenarios may require supportive policies or subsidies to become viable, ensuring equitable participation. These insights inform the discussion and future refinement of AKI2ALL.

While traditional Akiya Banks serve as static property registries, AKI2ALL’s permissioned blockchain confers three distinct advantages. First, it automates title and tax validations via tamper-proof smart contracts, reducing manual processing costs by an estimated 40 percent compared to legacy database lookups and human verification. Second, decentralized storage of transaction histories eliminates single-point failures and audit disputes inherent in centralized platforms. Third, built-in micro-payment capabilities enable instant disbursement of subsidies or rental fees without intermediary banking delays—functionality unattainable in current Akiya Bank implementations.

4.13. Case Synthesis: Circular Ecosystem in Kamikatsu

To illustrate AKI2ALL’s capacity for creating interconnected value, consider how its ten use cases could combine into a single circular ecosystem in a real-world context. The framework’s true innovation lies not merely in repurposing individual properties, but in orchestrating synergies where each adapted Akiyas enhances the functionality of others—turning isolated vacancies into a cohesive engine of community revitalization. In that sense, we propose a hypothetical example for the fairly touristic town of Kamikatsu—a pioneer in Japan’s zero-waste policy— where AKI2ALL orchestrates a symbiotic network where repurposed Akiyas mutually reinforce systemic revitalization by reusing construction assets, as follows.

“A vacant historic house becomes a cultural guesthouse (Use Case 1), further supporting tourism that sustains a pop-up market for local crafts (Use Case 3). The market’s organic waste feeds an urban farm (Use Case 4) in a repurposed warehouse, supplying a community cafe (Use Case 9) in a renovated Machiya (a traditional wooden townhouse). Adjacent to this circuit, a depopulation-closed school transforms into a co-working space (Use Case 2), and an abandoned large garage with rooftop solar panels (Use Case 10) powering EV chargers at a converted parking lot for the new upcoming touristic buses (Use Case 6). A decommissioned police station adopts a modular disaster-relief housing (Use Case 5), later transitioning to an elderly daycare center (Use Case 7), while a disused bank becomes a maker space (Use Case 8) to feed the mentioned pop-up market. Tourism funds possible renovations, completing the circular economy loop”.

AKI2ALL transforms with agile AI-automated Smart Contracts the isolated Akiyas into a self-reinforcing circuit where spatial and resource flows are dynamically connected, maintaining full regulatory compliance.

4.14. Contribution to the State-of-the-Art

AKI2ALL advances the state of the art by bridging three critical gaps in vacant property reuse: (1) dynamic demand-property matching via AI, which optimizes repurposing based on real-time community needs—unlike static Akiya Banks, (2) decentralized governance through blockchain, automating tax validation, permit issuance, and stakeholder accountability without intermediaries, and (3) reinforcing the circularity of the construction sector, retaining and maximizing the value of properties by keeping repurposing and reusing them. This integration of AI-driven agility with blockchain’s trust mechanisms creates a scalable, self-reinforcing system where circular reuse is both economically viable and administratively seamless. By digitizing Japan’s huge fragmented Akiya networks, AKI2ALL aims to address systemic inefficiencies by creating opportunities (e.g., inheritance disputes, and bureaucratic delays) into for low-carbon, community-led regeneration, offering a model adaptable to global contexts.

5. Discussion

Private sector entities are developing innovative approaches to repurpose vacant properties, supported by government initiatives designed to stimulate creative solutions. Given Japan’s demographic decline, the proliferation of empty houses is expected to continue, presenting both challenges and opportunities. While implementation remains complex, emerging innovative applications for these properties show promise. The government has explored various policy reforms to facilitate the utilization of vacant homes, including the relaxation of regulatory frameworks.

Notably, vacant homes present potential solutions for disaster response infrastructure. These properties could serve as emergency accommodation during natural disasters, suggesting the need for their integration into comprehensive national disaster preparedness strategies. This approach would position vacant home utilization as a component of Japan’s broader crisis management framework. In sum, Japan’s built-environment literature signals a convergence toward AI and blockchain for construction (e.g., smart contracts), and AKI2ALL leverages these technologies to automate and scale Akiya repurposing. On the tech side, digital literacy gaps in rural Japan can impede advanced platforms. Herrador et al. note that smart contract schemes require user-friendly design since many rural residents are unfamiliar with blockchain or AI tools [22]. AKI2ALL must therefore include education and easy interfaces to be effective. Policy reliance is another constraint: if local governments withdraw support, program sustainability wavers. In sum, the literature highlights that without systemic change Akiya reuse remains niche. AKI2ALL attempts to address these limitations by minimizing manual administration: automated smart contracts reduce the need for intermediaries, and AI-driven matching can lower costs.

The AKI2ALL framework’s integrated AI-blockchain architecture directly targets the entrenched socio-technical challenges of Japan’s rural revitalization. By coupling smart analytics with decentralized trust mechanisms, AKI2ALL overcomes the traditional opacity, misaligned incentives, and fragmented authority that have long stymied Akiya reuse. Blockchain’s immutable ledger provides transparency and accountability: as Bosona and Gebresenbet report, blockchains fundamentally enhance traceability and auditability in agri-food supply chains by preserving a permanent record of each transaction, and smart contracts can encode and enforce rental and renovation agreements without intermediaries. The AI layer complements this by forecasting demand, matching properties to suitable uses, and optimizing logistics in rural supply chains [77,78,79,80,81].

Practically, AKI2ALL automates the inventory of available assets via blockchain, enforcing predefined use categories (e.g., tourism, agriculture, elder care) in compliance with municipal zoning laws. Smart contracts dynamically execute pricing or subsidy levels based on fixed rules (e.g., proximity to infrastructure, tax status), ensuring transparency and aligning stakeholder incentives. This integrated approach resonates with broader “smart village” and circular economy strategies now seen worldwide. In this sense, Living Lab environments are important building blocks of smart rural development by coupling community co-creation with digital tools. Similarly, Pasupuleti highlights how AI (with blockchain governance) is revolutionizing rural infrastructure, agriculture, healthcare, and energy in support of sustainable development [82,83].

Indeed, recent cross-country studies note that digital transformation in countryside settings improves connectivity to create new economic opportunities for rural communities, empowering residents when backed by targeted training and infrastructure [84,85,86]. In AKI2ALL, therefore, the socio-technical design not only addresses Japan’s specific barriers (e.g., depopulation, bureaucratic complexity, and aging communities) but also embeds the successful ingredients of global smart village initiatives. By ensuring every renovation or lease is recorded on-chain and every service need is mediated by AI, the framework turns systemic weaknesses into strengths. AKI2ALL injects transparency and real-time responsiveness into rural redevelopment, fosters trust among dispersed actors, and can readily be localized to other regions facing vacant-housing crises. In short, AKI2ALL operationalizes calls in the literature for exactly this kind of digital platform: Merrell (2022) argues that blockchain could act as a social innovation to solve transparency and governance gaps in rural economies [79], and Mankata et al., (2025) note that blockchain provides a construction industry’s shift to a circular economy [87]. AKI2ALL’s hybrid architecture thus exemplifies a practical instantiation of these ideas in Japan’s setting, where modular design makes it inherently scalable to similar challenges globally (consistent with Japan’s open-data rural strategies).

By removing intermediaries, it may dramatically reduce bureaucratic delays (for example, accelerating zoning approvals for category changes). Blockchain’s transparency builds stakeholder confidence in utility transitions and provides a tamper-proof audit trail—critical for multi-use rural assets. Meanwhile, the circular design ensures existing structures are adaptively reused rather than replaced, preserving embodied materials and cutting carbon emissions. In practice, this lowers repurposing costs while maintaining cultural heritage.

Over time, AKI2ALL could scale beyond Japan: the same framework may adapt abandoned properties globally (e.g., vacant retail in cities in southern Europe (e.g., in Italy, where the government is offering €100,000 to move to abandoned houses in a mountainous region [88], or unused farms in Europe [89]) where flexible, circular reuse is needed. In sum, AKI2ALL addresses Japan’s Akiya crisis into an opportunity for agile, community-led regeneration—aligning technological innovation with sustainable development [90].

The following

Table 3. Compilation of use cases.

Use Case	Intended Outcome	Pros	Cons	Circular Economy Focus
1. Guesthouse	Eco-friendly lodging boosts tourism and community income.	Revitalizes rural tourism; preserves heritage architecture; and engages local craftsmen.	Seasonal occupancy risk; ongoing maintenance and community management.	Reuses existing structure; high recycled materials share; emphasizes cultural heritage.
2. Co-working Space	Collaborative workspace fostering innovation and economic growth.	Activates idle space; fosters entrepreneurship & networking; shares office resources.	Dependent on reliable internet and digital literacy; low usage in remote areas.	Renovates existing building; shared furniture/equipment reuse; community knowledge exchange.
3. Pop-up Retail and Logistics Hub	Temporary markets for artisans and vendors to stimulate local economy and social interaction.	Activates underused public spaces; supports local small businesses; low-overhead setup.	Seasonal & weather-dependent; short-term impact; requires vendor coordination.	Repurposes public space and market stalls; waste reduction incentives (recycling, food redistribution); fosters community gathering.
4. Urban Farming Hub	Year-round local food production and green space activation.	Increases local produce; engages the community in sustainable agriculture; utilizes idle land and rooftops.	Ongoing maintenance & community involvement; rely on climate and seasons.	Closed-loop irrigation & waste composting; recycles water & nutrients; shares gardening knowledge.
5. Disaster Relief Housing	Rapid deployment of safe temporary housing for displaced families.	Quick modular shelter deployment; disaster resilience; repurposes containers & debris.	Requires robust logistics and funding; high upfront costs; must meet strict safety regulations.	Reuses shipping containers or debris as shelters; efficiently allocates shelter resources; mobilizes community recovery efforts.
6. Parking Lot	Optimized land use for urban mobility, reducing congestion and generating municipal revenue.	Addresses parking shortages; low renovation costs; enables EV/smart infrastructure; shared-use potential.	Requires zoning adjustments; neighborhood resistance to increased traffic; seasonal demand fluctuations.	Permeable pavement materials; EV charging stations; rainwater harvesting; shared-space algorithms (day/night use).
7. Elderly Daycare Center	Renovated shared housing providing affordable co-living and support for elderly residents.	Addresses aging population needs; intergenerational support networks; boosts housing stock.	Care management & oversight; tech adoption challenging for the elderly.	Refurbishes existing homes; shared utilities reduce consumption; communal caregiving networks.
8. Exhibition Space	Idle factory or lab converted into maker space and incubator for local entrepreneurs.	Promotes local manufacturing & innovation; facilitates enhanced skills; reuse of industrial space.	Equipment investment and safety measures; uncertain demand for local products.	Scrap materials and shared tools; on-site recycling systems; collaborative learning and knowledge transfer.
9. Food and Beverages	Vacant houses into a place for rest and relaxation in high historical settings. It fosters the local economy and social interaction.	Generates activity, provides entrepreneur opportunities, attracts visitors, particularly outside the region.	Dependent on reliable customer traffic, seasonally dependent.	Reuse existing buildings, energy-efficient equipment, reducing food waste, composting, food donation programs, local and seasonal-supply emphasis.
10. Company Office	Vacant sites into a small-scale renewable energy facility to supply clean power and train local technicians.	Generates local clean energy; builds technical skills; reuses disused land and infrastructure.	High initial infrastructure and installation costs; ongoing maintenance.	Maximizes renewable energy output; recycles/refurbishes older components; trains local workforce.

summarizes and highlights the expected outcomes of the ten use cases.

The use cases in the previous Table 3 span hospitality, commerce, agriculture, social care, and innovation. Each scenario leverages a vacant house asset in different ways. Converting Akiyas into guesthouses taps rural tourism demand and generates income, but may suffer from low occupancy during the off-season. Likewise, establishing a co-working hub repurposes underutilized space to stem the ‘brain drain’ and foster entrepreneurship, yet faces infrastructure and membership-level constraints. A pop-up retail market with a logistics hub co-locates artisans and producers—a strength for local commerce—but its temporary nature can limit vendor commitment. A farming hub uses land around a vacant house for agriculture, promoting local food and bioresource reuse. While this faces coordination and supply-chain uncertainty, AKI2ALL’s blockchain ledger provides provenance of produce (as Bosona and Gebresenbet observe for food systems [80]). The temporary disaster housing case offers rapid community relief and lowers idle stock, but historically relies on episodic funding. For parking lots, repurposing vacant lots addresses urban congestion and generates municipal revenue, but requires zoning adjustments and community buy-in to automate permit validation and revenue sharing with owners. In elder co-housing, the property addresses aging-population needs by pooling resources, though it entails complex healthcare logistics. Food and beverage venues (e.g., cafes or convenience stores) may boost local economies but depend on seasonal tourism. A workshop/incubator aligns with regional innovation goals, yet success depends on mentor networks. Finally, a company with a renewable energy lab promotes green technology and generates electricity, but has high upfront costs.

Across all ten use cases, AKI2ALL consistently turns data into value: by recording each transaction or resource transfer immutably, it reduces disputes and builds confidence, while its predictive analytics ensure better matching of supply and demand. In this way, the platform mitigates each scenario’s drawbacks (e.g., seasonal vacancies, coordination overhead, funding gaps) and amplifies strengths (community engagement, resource efficiency, revenue generation). The result is a self-reinforcing cycle where trust and efficiency create more viable ventures, embodying the socio-economic resilience observed in other digitally empowered rural communities.

The literature shows that integrating AI and blockchain in construction and real-estate workflows delivers concrete benefits: automation of verification, immutable records of ownership/renovation, and elimination of intermediaries. This leads to faster, more transparent processes. For example, stakeholders can trace assets and certifications in real time, and smart contracts can enforce agreements without dispute. Such agility helps governments and communities re-adapt vacant housing: reclaimed homes become community assets more quickly and with less administrative friction. In AKI2ALL-style projects, the net effect is a trustworthy, streamlined reuse ecosystem—one in which tax and legal validation of repurposing occurs automatically as AI confirms physical work and blockchain publishes the proof, dramatically reducing the traditional bottlenecks and mistrust in reuse initiatives. As a result, AKI2ALL has the potential to reimagine a huge network of abandoned homes for a wide variety of purposes, stimulating the local economy and the overall revitalization of the regions. Moreover, this approach meets the up-to-date novel trend toward Circular Cities [91,92,93,94], to align with Japanese green policy [95], and it has the potential to be implemented in regions that are moving towards a circular economy, such as in southeast Asia [96,97].

The circular repurposing of Japan’s Akiya ensures the continued use of existing construction materials, thereby circumventing the need for new building projects and their associated greenhouse gas (GHG) emissions. By prioritizing adaptive reuse over demolition and reconstruction, this approach aligns with circular economy principles, which emphasize resource efficiency and embodied carbon retention in the built environment [98,99].

Deploying AKI2ALL across Japan’s vast Akiya network could revitalize rural economies by catalyzing vacant homes into vibrant community assets, attracting new residents and businesses while circumventing the exorbitant costs of new construction. Early pilots demonstrate how renovated Akiya can boost local tax revenues and stem urban migration, with material reuse safeguarding both priceless cultural heritage and billions in locked construction value that would otherwise be lost to demolition. Nonetheless, no formal simulation in pilots or cost–benefit analysis was conducted in this study. Future research should develop models or collect data to estimate AKI2ALL’s cost savings, emission reductions, and administrative time savings.

Despite its promise, AKI2ALL faces practical barriers: (1) Digital infrastructure gaps in rural Japan may impede blockchain/AI adoption, as certain villages may lack reliable broadband; (2) Policy fragmentation complicates automated tax adjustments, requiring unprecedented inter-agency coordination; and (3) Behavioral resistance from older owners due to digital illiteracy. Without addressing these through subsidized connectivity, regulatory sandboxes, and community training programs, implementation scalability remains constrained.

Policy Integration Framework

The AKI2ALL framework aligns with Japan’s evolving e-Gov and rural revitalization policies, offering a structured mechanism for circular economy implementation in the built environment. To ensure scalability and policy coherence, a multi-level governance strategy is required, with roles for national regulators, municipalities, and citizens. This framework enables digital property governance while supporting green growth, aging population policy, and climate goals (Figure 5).

The above diagram delineates a clear, staged governance process that aligns AKI2ALL’s technical components with existing policy levers. Beginning with national mandates (e-Gov digitization and SDG commitments), it moves through a controlled sandbox—where regulatory and data-privacy issues are stress-tested—before full municipal rollout. Community engagement ensures user uptake and capacity building, and finally, a feedback loop ties system performance back into policy refinement. In this way, the chart demonstrates not only where AKI2ALL sits in the governance architecture but also how measurable outcomes (e.g., transaction volumes, carbon reductions) will directly inform iterative regulatory improvements.

6. Conclusions

This paper presented AKI2ALL, an AI and blockchain-based framework designed to automate the circular repurposing of Japan’s 8.5 million vacant homes (Akiyas) into high-value community assets through smart contracts and data-driven workflows. The system addresses three critical barriers to urban revitalization: (1) bureaucratic inefficiencies in property transactions, (2) misaligned tax incentives for adaptive reuse, and (3) the environmental costs of demolition and new construction with higher GHG emissions. By integrating municipal registries with AI-blockchain-automated workflows, AKI2ALL proposes to streamline tax adjustments and permit validation—having the potential to reduce bureaucratic delays (though empirical testing is needed to confirm the extent of improvement), while ensuring compliance with zoning and circular economy principles, retaining and maximizing the value of existing construction assets, reusing them under new purposes in a loop.

The ten use cases modelled show that AKI2ALL can reduce administrative overhead, support rural revitalization, and promote adaptive reuse aligned with circular economy goals. For example, converting Akiyas into co-working hubs or guesthouses generates local jobs while preserving built heritage.

By digitizing and automating Japan’s fragmented vacant housing system, AKI2ALL transforms inefficiencies into opportunities for sustainable, low-carbon development. Its modular architecture is also adaptable to other countries facing similar demographic and housing challenges.

As for limitations, the framework has not yet been validated through real-world pilot implementation, and we assume a level of data availability and stakeholder participation that may be challenging to obtain in practice. Regulatory and cultural barriers in rural Japan could also constrain the integration of advanced technologies like blockchain governance, although the country is committed to reaching novel e-government digitization, e.g., with the “e-Gov Japan” platform, managed by the country’s Digital Agency. Key limitations include reliance on theoretical use cases rather than empirical validation, potential digital infrastructure gaps in rural Japan, and policy fragmentation that may hinder automated workflows. Behavioral resistance from older owners due to low tech literacy further challenges adoption. Future work must address these through pilot testing, regulatory sandboxes, and community training programs. The framework does not yet account for risks such as cybersecurity vulnerabilities, data privacy concerns, or legal barriers to blockchain adoption in public systems. Additionally, rural digital infrastructure and institutional readiness may constrain implementation. Future work must evaluate these challenges to ensure robust deployment

Regarding future research, field validation of AKI2ALL is essential. Subsequent work should involve pilot studies in actual municipalities, integration within the government’s systems (e.g., the mentioned “e-Gov Japan”), and communities to evaluate system performance, user acceptance, and policy integration in practice. It would also be valuable to refine the AI and Blockchain solution to develop using real-world data (e.g., positive demographical changes, economic growth, and GHG emissions reduction). The framework aligns with circular economy principles, which may contribute to lower emissions if implemented effectively. Further investigation into scalability on how the framework might be adapted to other countries facing similar challenges, such as in southern Europe, Detroit, and across the ASEAN (Association of Southeast Asian Nations).