Success Factors and Sustainability of the K-Pop Industry: A Structural Equation Model and Fuzzy Set Analysis

: As the popularity of K-pop grows, the industry is contributing to the positive perceptions of South Korea’s overall national brand value. This has led to it being considered a strategic industry worth cultivating. However, many people are unsure of its sustainability. To address this, our study investigates the factors that are key to the industry’s success—K-pop industry success factors—and their relationship with sustainability (SNS citizenship behavior and tourist behavioral intention). The study surveyed 1247 global viewers (eight countries) who listen to K-pop via TV, radio, and the Internet, watch K-pop videos on YouTube, and search information related to K-pop on SNS. The collected data were analyzed using two statistical techniques: structural equation model (SEM) analysis and fuzzy set-quality comparative analysis (fsQCA). (1) According to the SEM analysis, of the K-pop success factors, three factors demonstrated a statistically signiﬁcant positive inﬂuence on SNS citizenship behavior: casting, producing/promotion, and content. (2) SNS citizenship behavior showed a statistically signiﬁcant positive inﬂuence on tourist behavioral intention. (3) According to the fsQCA results, casting, training, social media, content, and SNS citizenship behavior were commonly derived at least three times, indicating that these are key factors impacting tourist behavioral intention. (4) In summary, results conﬁrmed that, with the exception of producers, the ﬁve K-pop success factors, casting, training, producing/promotion, social media, and content, are crucial to sustainability and to increasing tourist behavioral intention.


Introduction
K-pop, or Korean pop music, refers to popular music that has gained mainstream popularity in South Korea, also simply referred to as gayo (歌謠). Popular music from the Anglosphere is called pop in Korean, and popular music from countries outside the Anglosphere are named by attaching the country's initial to "pop." Thus, the term "K-pop" was born [1,2]. As Korean pop songs have gained popularity overseas, K-pop has become widely recognized and consumed in other countries [1,2].
In the past, K-pop's overseas expansion was concentrated only in Asia [3]. Today, however, K-pop has developed a following of loyal fans around the world, across several nationalities [4]. Similar to pop genres borne in the U.S. and Europe, K-pop has been able to extend beyond Asia and become a new type of global pop [5].
Today, K-pop idols' singing and dancing are no longer unfamiliar in the U.S., Canada, Europe, South America, and even Africa [4]. However, there are still many questions regarding the sustainability of South Korea's K-pop industry [5]. Although it has clearly won the adoration of many fans around the world, it is inaccurate to say that it has risen to the top of the global music market [6]. As much as K-pop is consumed at high

RQ1. What is the influence of K-pop success factors on SNS citizenship behavior, a sustainability variable, as perceived by global viewers?
RQ2. What is the influence of SNS citizenship behavior on tourist behavioral intention, a sustainability variable, as perceived by global viewers?

K-Pop Success Factors
A key question is: How did K-pop break through language and cultural barriers to succeed in the global music market? To answer this, we analyze the success factors of K-pop from the perspectives of production, consumption, and distribution. To this end, we applied the "cultural diamond" model frequently used when analyzing cultural phenomena factors in the sociology of art [30,31]. As shown in Figure 1, we developed a K-pop cultural diamond model, which consists of four points connected by lines to create the diamond. The points are the derived success factors, which include creators and content, the consumers, and their SNS citizenship behavior, the sustainability variable. These figure elements can be explained as follows. (1) Producers. These are the key players in the industry for K-pop's success in overseas markets. These entertainment agencies are responsible for systematizing the entire production process of casting, training, producing, and promotion for overseas markets [6,21,26,32]. That is, entertainment agencies have systematized the production process and carefully prepared to enter overseas markets from a long-term perspective. Specifically, many studies have described Korea's welldeveloped system of intense training of possible K-pop idols to pick out just a few stars to create a differentiated competitive advantage [6,21,26,32]. The implication is that, even from the planning stage, agencies target the global market and polish the skills of idol groups. The specifics of the systematization of the entire production process, from casting to promotion, include the following.
(a) In terms of casting, agencies focus on discovering hidden "gems." They devote their efforts to discovering talent, assuming that "half of all quality gems would be successful." They also hold global auditions to discover talent overseas [32]. (b) In terms of training, agencies have looked at the best entertainers as long-term investments. These agencies act as powerful gatekeepers, cultivating only the best uncovered "gems" from among many potential idols while pouring money and investment into development training [26].
(c) In terms of producing, the K-pop industry sources talent globally for its creative needs. Agencies maximize the quality of K-pop albums by involving the world's premier experts in each artistic field. They divide the production stage labor using a wide range of experts from various nationalities and fields [6]. (d) In terms of promotion, the industry utilizes a network of local partners. With the aim of ultimately entering the international market, even at the first planning stage, agencies minimize the uncertainty and risk of overseas expansion through partnerships with local companies. They also have overcome cultural barriers in the short term by releasing albums specialized for local markets [21].
(2) Distribution. Agencies have reduced their costs and the time of overseas expansion by actively utilizing social media, enabling fans to easily and voluntarily spread content. Namely, agencies use the social media platforms YouTube, Facebook, and Twitter to reduce their costs and the time required to expand overseas. Notably, entertainment agencies have recognized social media as the core platform for K-pop consumption. This means that they use this as their key distribution channel and produce content suitable for this media [9,14,33].
(3) Consumers. The K-pop consumers are familiar with technology, enjoy the K-pop culture, and freely express their opinions, allowing its popularity to spread quickly. In other words, K-pop's main consumers are social media and technology savvy. They not only listen to and admire K-pop, but are also part of a new culture of entertainment where K-pop is the subject. In some European and South American countries where there are no customized promotions or local expansion, the local consumers have created online fan clubs on social media to share opinions and comments [15,34,35].
(4) Content. Based on three key factors, namely singing ability, choreography, and visuals, K-pop idols have transformed and captivated consumers worldwide. The K-pop industry has fused Western pop styles with easy melodies that suit Eastern sentiments, which has secured universal mass appeal and gained popularity across nationalities. K-pop provides showy spectacles through highly synchronized group dances and point dances. The industry has also continuously changed sensuous fashions and styles whenever new songs are released [13,16,18,36].
All of the above can be considered the K-pop industry's important success factors: the producers, casting, training, producing/promotion, social media, and content. The next question is: How do these six success factors influence SNS citizenship behavior, the sustainability variable, as perceived by global K-pop viewers? Ultimately, we want to discover whether tourist behavioral intention can be increased through such behavior.

Sustainability
Sustainability research is the study of whether nature can maintain diversity, productivity, balanced ecosystems, and proper functions [37][38][39]. The exploitation and destruction of nature, propelled by the development of science and technology, has exceeded the earth's capacity to purify itself and has resulted in the destruction of many ecosystems and other disasters. As a result, sustainability research has emerged to investigate how we can protect and live in harmony with the natural environment [37][38][39]. In other words, the field looks at the balance between the conflicting interests of sustainability and sustainable development and economic development and environmental protection [40][41][42][43].
In 2015, the United Nations proposed 17 Sustainable Development Goals [44]. Under the promise "leave no one behind," the plan has been to achieve these goals in both developed and developing countries by 2030 [45][46][47]. Looking at these 17 goals, we can see that sustainability does not only apply to environmental issues. The goals include the pursuit of balanced development in emerging countries and to create a world free of pain and discrimination based on gender, region, race, and nationality [45][46][47]. Table 1 presents these 17 goals. Among these goals, there are three that encompass the success factors for a sustainable K-pop industry, "Decent Work and Economic Growth," "Responsible Consumption and Production," and "Partnerships to achieve the Goal"; thus, these can be integrated into our study. In our study, we use SNS citizenship behavior as a parameter and tourist behavioral intention as the dependent variable for sustainability (sustainable behavior).

SNS Citizenship Behavior
Citizenship behavior refers to behavior that contributes to the psychological environment of an organization, such as helping others even when not required [48,49]. Citizenship behavior is covered mainly in organizational behavior research [50][51][52][53]. Such research covers the voluntary behaviors of the organization's members that enhance organizational efficiency, regardless of the official rewards provided by the organization. This includes behavior such as punctuality, assisting fellow colleagues, and refraining from arguing [50][51][52][53].
Customer citizenship behavior shifts the theory of organizational citizenship to the customer's perspective. Customer citizenship behavior refers to behaviors that customers voluntarily perform in the service delivery process [54,55]. Bettencourt [56] was the first to study organizational citizenship behavior from a customer perspective in terms of retail store customers. He explained that customer citizenship behavior includes the three concepts of customer loyalty, customer cooperation, and customer participation. Customer loyalty is customer behavior that demonstrates loyalty to and promotes an organization's interests beyond the customer's individual interests, signifying that the customer acts as a promoter of the company. Customer cooperation indicates the extent that customers trust and evaluate the company's delivery of services as competent, signifying that they enjoy performing a human resource role. Finally, customer participation is customer behavior such as active and responsible engagement in a service company's management and development activities in the role of consultant [56].
SNS citizenship behavior refers to the prosocial and responsible behaviors of SNS users who voluntarily engage in activities other than their roles on SNS [57,58]. As discussed above, this definition applies the basic theory and concept of organizational citizenship behavior to SNS, that is, behaviors other than work roles for enhancing organizational performance [57,58]. Here, we define SNS citizenship behavior as the degree that global viewers who search for K-pop-related information create new information or material related to K-pop and share it rapidly with others on SNS.
Based on the underlying theory of citizenship behavior in the context of the K-pop industry, we investigate the applicability of two sustainable development goals: "Responsible Consumption and Production" and "Partnerships to achieve the Goal." We hypothesize that, among global viewers who follow K-pop, when they are satisfied with their experiences, they are highly likely to continue to listen, watch, and talk about K-pop [2,59]. Additionally, sharing and providing information related to K-pop with others on SNS leads to voluntary SNS citizenship behavior [11,14,35,[60][61][62][63]. Such activities, like recommending K-pop to other global viewers or word of mouth, can increase consumer loyalty to K-pop [20,64]. This means that these behaviors can enable sustainable and responsible production related to K-pop. Thus, the sustainable global audience for K-pop can be built and expanded through SNS [9,65,66].

Tourist Behavioral Intention
Many scholars and social science studies have investigated behavioral intention, an outcome variable based on customer satisfaction [67][68][69][70]. In those, scholars often treat revisit intention and recommendation intention as the measurement variables [71][72][73]. Behavioral intention is also recognized as an intermediate variable between individual attitude and behavior, signifying the individual's subjective state. This is considered the individual's belief and will to engage in a specific future behavior [74][75][76][77]. It is also defined as customer loyalty, consisting of the reuse intention and the word-of-mouth intention. Specifically, favorable behavioral intention leads to recommendation to others, accompanying others, positive word of mouth, reuse, promotion of loyalty, and willingness to pay premium prices [78][79][80][81].
Tourism is defined as the act of temporarily leaving one's home to visit a new place for pleasure. Tourism is also used within the broader concept of travel, which includes visiting friends and relatives (VFR) and traveling for business [82]. Tourist behavioral intention can be defined as the process of searching, purchasing, using, evaluating, and disposing of products or services that tourists expect to meet their needs [82]. It can also be described as the internal or external behaviors arising from a tourist's purchase decision and final behavior in purchasing and using/consuming a product or service [83]. Tourist behavioral intention requires potential tourist characteristics and conditions that lead to tourism travel, such as cost, time, and information, which are essential to establishing a specific behavior. That is, once conditions related to cost, time, and information are satisfied, the subject's desire for a specific tourist behavior may increase. The assumption is that this increased desire leads to tourist behavioral intention [84,85]. Tourist behavioral intention also occurs from socialized needs. That is, economic conditions, time-related conditions, and stimuli from information provided by tourism businesses, which act as basic conditions for encouraging specific tourist behavior while influencing the desire for tourism. This resulting desire is connected to various stimuli and motivates tourism, ultimately leading to tourist behavioral intention [82,86,87].
In the context of K-pop, we define a tourist's behavioral intention as the individual's desire or plan to travel to South Korea [19,88,89]. Based on the underlying theory of behavioral intention, we investigate further whether the two sustainable development goals of "Decent Work and Economic Growth" and "Responsible Consumption and Production" are applicable to K-pop tourism. As discussed, K-pop has spread widely through SNS, such as YouTube, Facebook, and Twitter, with remarkable speed and has impacted the growth of the Korean Wave [7][8][9][10][11][12][13]. Namely, more tourists visit Korea to watch K-pop performances on SNS [25,90]. Consequently, South Korea's fashion, beauty, and medical care industries have been affected by this K-pop craze as well [13,91,92].
To encourage this phenomenon, companies are designing specific performances and products for overseas tourists that link K-pop content with tourist shopping; and these are garnering immense popularity [19,20]. The implication is that the K-pop craze can promote sustainable economic growth in Korea's cultural industries and culture and arts sector as well as fuel high-quality jobs [93,94]. Tourists visiting Korea, driven by the K-pop craze, engage in sustainable consumption in other industries such as K-pop-related fashion, beauty, and medical care [19,20].

Current Research
Kim [95] conducted a study on K-pop's success factors and effective overseas expansion strategies. According to that study, the two factors that led to K-pop's successful overseas expansion were (a) competitiveness of K-pop contents (content) and (b) K-pop media strategy. The competitiveness of K-pop content was divided further into (a) global localization strategy (producing/promotion), (b) idol development system (casting), and (c) competitiveness of K-pop stars (training). The most eye-catching aspect of K-pop's charm among global fans has been the "idol groups' performances" (content). Meanwhile, in terms of "K-pop media strategy," the study found that the spread of K-pop was accelerated through the adept usage of social media. These success factors give rise to voluntary citizenship behavior, including sharing information in real time among global fans on SNS, and play a crucial role in K-pop's overseas expansion success.
Jun [96] conducted a study on the factors of K-pop's overseas expansion based on the "diamond model." According to that study, K-pop's overseas expansion factors include (a) internationalization strategy (targeting overseas markets), (b) evolution of the management system (emergence of corporate entertainment agencies, systemization/specialization of organizations), the training system (star production system through training, open audition programs by entertainment agencies/broadcasters), and globalization of production (collaboration with overseas experts for production). In terms of content, the study mentioned the following factors as essential in K-pop's overseas expansion: (a) sincerity in the idol singer's lyrics and storytelling throughout the album (creating bonds of sympathy), (b) visual elements such as song and dance (performance), and (c) the idol singer's personality (e.g., appearance, talent).
In researching the global K-pop fans as consumers, the studies report a shift from passive consumers to active ones, indicating that communication and information sharing between fans and the K-pop idols through SNS is underway. In fact, the influence of the SNS media such as YouTube and others has shifted the paradigm of K-pop distribution and led to fans' active participation. As a result, global K-pop fans share information via SNS and naturally end up engaging in SNS citizenship behavior.
As noted earlier, citizenship behavior is behavior that contributes to the psychological environment of an organization, such as helping others voluntarily [48]. It is vital because it creates common values and enhances efficiency [49][50][51][52][53]. Over time, scholars have begun to study customer citizenship behavior from a marketing perspective [54,55]. Balaji [97] described customer citizenship behavior as the voluntary behavior of customers who do not receive explicit customer benefits. Studies have reported that these behaviors have a significant influence on the interests and performance of companies and even improve the quality of service [55,98,99]. Considering this, we use tourist behavioral intention as an outcome variable of SNS citizenship behavior, which ultimately relates to the customer's loyalty behavior. Based on the above discussion, we posed the following hypotheses.

Hypotheses
Hypothesis 1 (H1). Producers will have a positive influence on SNS citizenship behavior, a sustainability variable.
Hypothesis 2 (H2). Casting will have a positive influence on SNS citizenship behavior, a sustainability variable.

Hypothesis 3 (H3).
Training will have a positive influence on SNS citizenship behavior, a sustainability variable.

Hypothesis 4 (H4).
Producing/promotion will have a positive influence on SNS citizenship behavior, a sustainability variable.
Hypothesis 5 (H5). Social media will have a positive influence on SNS citizenship behavior, a sustainability variable.
Hypothesis 6 (H6). Content will have a positive influence on SNS citizenship behavior, a sustainability variable.
Hypothesis 7 (H7). SNS citizenship behavior will have a positive influence on tourist behavioral intention, a sustainability variable.

Research Model
Underlying our research methodology with the theoretical concepts referenced above and variables in existing studies, we designed a research model to investigate the perspectives of global viewers who listen to K-pop via TV, radio, and the internet, watch K-pop videos on YouTube, and search information related to K-pop on SNS. To this end, we developed a questionnaire survey to collect data from K-pop fans. We then empirically analyzed how the success factors of K-pop as perceived by these global K-pop viewers influenced sustainability (SNS citizenship behavior and tourist behavioral intention variables). Ultimately, we investigated how K-pop SNS citizenship behavior influenced tourist behavioral intention. Our research model is shown in Figure 2.

Survey Design and Measurement
To measure K-pop perceptions, our questionnaire survey included variables based on prior research that we modified and supplemented according to the purpose of this study. The survey comprised seven variables measured by four items, with the exception of SNS citizenship measured by five items. The 37 items were each measured on a 5-point Likert scale (1 = Not at all to 5 = Very much). Table 2 shows the operational definitions and measurements of the variables used in this study. Chang [100] Kim [101] Korea carefully prepared to enter the overseas market from a long-term perspective for the K-pop craze.
From the planning stage, Korea targeted the global market and polished the skills of idol groups for the K-pop craze.
Korea systemized the entire manufacturing process forming promotion for the K-pop craze.

Casting
Degree of various efforts to discover K-pop talent For the K-pop craze, Korea fully devoted its efforts to discovering talent, recognizing that half of all uncovered gems would be successful.
Chang [100] Kim [101] Kim [102] For the K-pop craze, Korea selected trainees through various channels, including official auditions and the recommendations of acquainted celebrities.
For the K-pop craze, Korea prioritized talent and hidden potential in its evaluations.
Korea actively discovered overseas talent through global auditions for the K-pop craze.

Training
Degree of comprehensive training to develop K-pop talent Korean agencies played the role of a powerful gatekeeper for the K-pop craze.
Chang [100] For the K-pop craze, dedicated teams of experts in Korea provided training focused on, for example, singing, dancing, and English.
For the K-pop craze, Korea trained trainees intensely in a continuous survival style.
For the K-pop craze, Korea divided roles such as singing, acting, and choreography based on the trainees strongest talents and combined them to create the best synergy.

Producing/ promotion
Degree of production of high-quality albums and wide promotions suited for the global market in relation to K-pop For the K-pop craze, Korea maximized the quality of albums by involving the world's premier experts in each creative field.
Chang [100] For the K-pop craze, Korea overcame cultural barriers in a short period of time by releasing albums specialized for local markets.
For the K-pop craze, Korea optimized, for example, lyrics, music videos, and fashion for local cultures in album production.  [106] For the K-pop craze, Korea has secured universal mass appeal that can gain popularity across nationalities.
For the K-pop craze, Korea has provided showy spectacles through highly synchronized group dances and point dances.
For the K-pop craze, Korea has constantly changed sensuous fashions and styles when a new song is released.

SNS citizenship behavior
The degree to which good information or a material related to K-pop is produced and rapidly shared on SNS I will share and provide K-pop-related information to people around me through SNS sites.
Kim et al. [58] I will share positive opinions about K-pop-related information to people around me through SNS sites.
I will always think about how to share K-pop-related information to people around me through SNS sites.
I will extract, process, and then share the core content of K-pop-related information to people around me through SNS sites.
I will always think about whether K-pop-related information can be helpful to people around me through SNS sites.

Survey Respondents
The study participants were global viewers who listen, watch, and discuss K-pop. We conducted two rounds of the survey from October 2019 to October 2020 using Entrust Survey (http://entrustsurvey.com accessed on 23 October 2019) and Netpoint Enterprise Inc. (http://www.netpoint.co.kr/), global research agencies. The survey was provided in English or French. The respondents were from eight countries: the Philippines, Singapore, Australia, the UK, France, the U.S., Canada, and South Africa. From the two global research agencies, we received valid responses from 1247 participants. Table 3 shows the details of the collected valid sample.

Data Analysis
We analyzed the data using the programs IBM SPSS Ver. 18.0, SmartPLS Ver. 3.3.3, and fsQCA Ver. 3.0, as follows. First, we conducted a frequency analysis to examine the demographic characteristics, a reliability analysis using Cronbach's alpha to test the reliability of the metrics, and a factor analysis to test validity. Our procedures also included a correlation analysis to examine the closeness (i.e., correlation) of the variables. Finally, we used structural equation model (SEM) analysis to examine causality between the core variables of the study. We also carried out a fuzzy set-quality comparative analysis (fsQCA).

Reliability and Validity
We examined the reliability and validity of all variables in the study in relation to the survey items. The results are shown in Table 4. Based on the analysis, Cronbach's alpha for all variables was a minimum of 0.847, indicating very high reliability. In addition, the loading of each factor was a minimum of 0.802, also indicating high validity, and the average variance extracted (AVE) was at least 0.686. A multicollinearity analysis confirmed the properties closely related to the independent variables; the variance inflation factor (VIF) was 4.019 or less, indicating no multicollinearity problem. Therefore, we were able to verify the reliability and validity of the variables in the study.   Table 5 shows the results of the discriminant validity analysis (correlation analysis). Our results indicated that the AVE square root exceeded the correlation coefficient for each variable. This verified the discriminant validity of the variables in the study.  [19,20,[107][108][109].

Correlation Analysis
As detailed in Table 6, the results of the SEM analysis are as follows. First, among the success factors of K-pop, casting (β = 0.326, t = 6.241, p < 0.01), producing/promotion (β = 0.223, t = 3.788, p < 0.01), and content (β = 0.107, t = 1.968, p < 0.10) showed a statistically significant positive effect on SNS citizenship behavior with casting (β = 0.326) having the greatest influence on it. In contrast, producers, training, and social media did not have a statistically significant effect on SNS citizenship behavior. This meant that Hypothesis 2, Hypothesis 4, and Hypothesis 6 were supported, whereas Hypothesis 1, Hypothesis 3, and Hypothesis 5 were not. Second, SNS citizenship behavior (β = 0.499, t = 19.464, p < 0.01) had a statistically significant positive influence on tourist behavioral intention. Therefore, Hypothesis 7 was supported.

Mediated Effect Test
In addition, we analyzed whether SNS citizenship behavior had a mediated effect in the relationship between the success factors of K-pop and tourist behavioral intention using SmartPLS Ver. 3.3.3. Table 7 shows the results, revealing that the three factors, casting, producing/promotion, and content, all had mediated effects in the path of K-pop success factors → SNS citizenship behavior → tourist behavioral intention. This means that these three factors increased SNS citizenship behavior, through which tourist behavioral intention would also increase. In contrast, the three factors, producers, training, and social media, did not have any mediated effect in the path of K-pop success factors → SNS citizenship behavior → tourist behavioral intention.

Fuzzy Set-Quality Comparative Analysis (fsQCA)
To determine the models of the explanatory variables leading to high tourist behavioral intention, the outcome variable, we set the explanatory variables as the K-pop success factors (producers, casting, training, producing/promotion, social media, and content) and SNS citizenship behavior and performed the fsQCA. Regarding fsQCA, a standard analysis was conducted and the results of an intermediate solution were confirmed [110]. Table 8 shows the results.
First, there were three models (Models 1 to 3) leading to high tourist behavioral intention. The solution coverage was 0.749 and the solution consistency was 0.897. As these exceed the recommended coverage and consistency levels of 0.2 and 0.8, respectively, the results were deemed suitable [111].   In summary, according to the fsQCA results, casting, training, social media, content, and SNS citizenship behavior were commonly derived at least three times, indicating that they were key factors impacting tourist behavioral intention. We also observed based on the SEM and fsQCA results that with the exception of producers, the five success factors of K-pop (casting, training, producing/promotion, social media, and content) were crucial in increasing tourist behavioral intention.

Summary of Research
Current research has failed to determine empirically the success factors for the Kpop industry linked to sustainability, that is, sustainable behavior (e.g., SNS citizenship behavior and tourist behavioral intention). To fill this gap, we investigated the success factors of K-pop (producers, casting, training, producing/promotion, social media, and content) and sustainability (sustainable behavior).
To this end, we surveyed 1247 global viewers (629 females, 50.4%) who listen to K-pop via TV, radio, and on the internet, watch K-pop videos on YouTube, and search information related to K-pop on SNS. The survey respondents were from eight countries: the Philippines, Singapore, Australia, the UK, France, the U.S., Canada, and South Africa. We analyzed the collected data using two statistical techniques: SEM analysis and fsQCA.
The key results were as follows: first, according to the SEM, of the K-pop success factors, three factors demonstrated a statistically significant positive influence on SNS citizenship behavior: casting, producing/promotion, and content. These findings support those of Jun [96] and Kim [95].
The details are as follows: (a) Entertainment agencies have selected trainees through diverse channels, such as official global auditions and recommendations by celebrities, and actively discovered (casting) foreign talent [32].
(b) Beginning in the song brainstorming stage, these agencies have collected various ideas from external sources and utilized diverse experts from different nationalities and fields to divide labor in the producing stage [6,20,21,26,32].
(c) Entertainment agencies have established partnerships with local leading entertainment agencies and record labels in target countries; the Korean agencies designed the overall concepts while the partners have carried out specific local promotions and secured distribution networks in local markets. They also optimized lyrics, music videos, fashion, for example, for the local culture, produced albums, and widely promoted the K-pop recorded in the local language in local dramas, movies, and commercials [6,20,21,26,32].
(d) By fusing Western pop styles with easy melodies that suit Eastern sentiments, the K-pop industry has ensured universal mass appeal that can gain popularity across nationalities. The industry also provides showy spectacles through highly synchronized group dances and point dances and constantly changes sensuous fashions and styles when new songs are released. The K-pop agencies also actively avoid sexual and violent elements common in R&B and hip-hop, mainstream genres of pop, emphasizing a differentiated message of innocence and passion. Thus, K-pop content is perfected based on three key factors: singing ability, choreography, and visuals [13,16,18,36].
In addition, the influence of new media, such as YouTube and other SNS platforms, has shifted the paradigm of K-pop distribution and led to fans' active participation [95,96]. Therefore, the three K-Pop success factors of casting, producing/promotion, and content maximize information sharing among global K-pop fans via SNS, which, in turn, naturally increases SNS citizenship behavior.
Second, SNS citizenship behavior also showed a statistically significant positive influence on tourist behavioral intention. We confirmed that there was a mediated effect in the path of casting, producing/promotion, content → SNS citizenship behavior → tourist behavioral intention. These findings support the research of Di et al. [98], Hur et al. [99], and van Tonder et al. [55]. In looking at the K-pop success factors, we found that the higher the perceptions of the casting, producing/promotion, and content, the more satisfied the global K-pop fans were with K-pop. In other words, these factors lead to voluntary SNS citizenship behavior. As global K-pop fans attach themselves emotionally to their favorite K-pop idols and search continuously for various K-pop-related information, voluntary SNS citizenship behavior arises. Thus, among the K-pop success factors, as the level of casting, producing/promotion, and content increases, fans become more likely to voluntarily engage in SNS citizenship behavior. These global K-pop fans reflect selfless, altruistic behavior on SNS. Their voluntary SNS citizenship behavior creates positive effects such as sustainable and responsible production related to K-pop [9,65,66], ultimately leading to tourist behavioral intention.
Third, according to the fsQCA results, casting, training, social media, content, and SNS citizenship behavior were commonly derived at least three times, marking them as key factors of tourist behavioral intention. In summary, the SEM and fsQCA results confirmed that, with the exception of producers, there are K-pop five success factors (casting, training, producing/promotion, social media, and content) that are crucial to increasing tourist behavioral intention. These findings are described in detail as follows: (a) Systematic casting/training. Entertainment agencies have systemized processes such as professionally casting and training trainees, and these idol groups have grown into differentiated K-pop talent [26,32]. (b) Promotional method. Agencies have reduced their costs and time in overseas expansion by utilizing social media, which enables fans to easily and voluntarily spread content [9,14,33]. (c) Active global K-pop fans. Global K-pop fans are familiar with technology, actively enjoy the culture, and freely express their intentions [15,34,35]. (d) K-pop content. K-pop content combines three key qualities: excellent singing ability, choreography, and visuals [13,16,18,36]. The implication is that, when these K-pop success factors are emphasized effectively, more global K-pop fans will be motivated to meet real K-pop stars and watch K-pop performances, which will lead to more fans visiting and traveling in Korea, thereby increasing tourism.

Research Contributions and Recommendations
This study provides the following theoretical and practical contributions. First, we analyzed the K-pop success factors from the perspectives of production, consumption, and distribution. That is, we applied the theory of the "cultural diamond" used when analyzing cultural phenomena in the sociology of art to support our investigation. To the best of our knowledge, this is the first study to use the cultural diamond model to study the K-pop industry, consisting of four vertices, then derive success factors and link them to sustainability, namely, SNS citizenship behavior and tourist behavioral intention.
Second, we looked at all 17 sustainability categories to identify those that would encompass the K-pop industry's success factors: "Decent Work and Economic Growth," "Responsible Consumption and Production," and "Partnerships to achieve the Goal." To the best of our knowledge, ours is the first study to apply "SNS citizenship behavior" as a parameter and "tourist behavioral intention" as a dependent variable to measure the industry's sustainability.
Third, we were able to demonstrate empirically that, as perceived by global viewers, the K-pop success factors increase SNS citizenship behavior and further lead to tourist behavioral intention. The implication is that necessary measures should be taken for sustainable hallyu tourism marketing, promotion, and product planning in connection with K-pop.
Our recommendations are as follows: (1) to induce consumers to visit or travel to Korea, support should be provided for enthusiastic fans of sustainable K-pop and foreign visitors participating in K-pop concerts should be properly managed; (2) further efforts are needed to build sites that provide K-pop information and integrated tourism information related to K-pop; (3) the planning of K-pop performances in connection with sustainable regional festivals and the development of hallyu tourism products related to K-pop, differentiated by target market, should be expanded; and (4) measures should be explored to promote hallyu tourism in connection with K-pop at a sustainable institutional level.
Fourth, a mediated effect was observed in the path of the K-pop success factors casting, producing/promotion, content→ SNS citizenship behavior → tourist behavioral intention. To sustain this, better management is needed among the entertainment agencies that handle K-pop performances for global K-pop fans. That is, some entertainment agencies that plan K-pop concerts and idol fan meetings have displayed irresponsible behavior with recruited customers and in their operations. This then damages global K-pop fans and erodes trust in the K-pop industry and Korea's national brand and image. This means that institutional measures for the management of entertainment agencies that handle K-pop performances are necessary. Furthermore, the roles and scope of work of these performance entertainment agencies should be defined, and the Fair Trade Commission should provide requirements for establishment approval. There is also a need for legal standards that clarify interests between sellers and buyers, such as compensation for damages when a performance is cancelled.
Fifth, over the past decade, Korean pop music (K-pop) has left unprecedented traces in the global pop market through the digital proliferation of highly-trained K-pop idols. In addition, English literature on K-pop has steadily increased, and the most recent K-pop phenomenon is focused on the spread of digital idols. [112]. In particular, the changes in the K-pop production environment brought by social media, as mentioned in the introduction, had a great impact. For example, a BTS music video uploaded to YouTube reached more than 1 million views in a single day. [16,18]. Furthermore, as the results of this study show, the fsQCA analysis revealed that social media is a key factor that can have a significant influence on tourism intention. Therefore, entertainment agencies must reduce costs and time when entering foreign markets by more actively utilizing social media through which marketing activities can be easily propagated. Furthermore, global viewers, especially those in their 20 s and 30 s, are familiar with IT and are active consumers. They eagerly embrace IT pop culture, and express their opinions freely. This suggests that entertainment agencies need to create a new IT pop culture, or entertainment culture that incorporates social media, rather than simply leaving consumers to listen to and accept K-pop.

Research Limitations and Future Directions
While this study provided several theoretical and practical contributions, it has some limitations as well. First, we investigated only certain K-pop success factors (producers, casting, training, producing/promotion, social media, and content) and sustainability. As we looked at only six success factors, more success factors should be investigated in future studies.
Second, we used "SNS citizenship behavior" as a parameter and "tourist behavioral intention" as a dependent variable for sustainability. However, as there are likely more parameters and dependent variables that can be applied for sustainability, more sustainability variables should be analyzed in the future.
Third, the participants of this study were 1247 global viewers from eight countries. As K-pop has become a wider global phenomenon, more global K-pop viewers of other nationalities should be surveyed for specific and generalized investigations. Additionally, for research accuracy, the model developed here could be improved by comparing it with a similar one in another country.
Fourth, based on the data collected, we used two statistical techniques: SEM analysis and fsQCA. However, other statistical techniques may offer differing results.