1. Introduction

Since the emergence of microblogging in 2009, China's self-media has developed rapidly, forming a situation in which various platforms have developed simultaneously. Among them, short video has also become the hottest self-media; according to the 51st Statistical Report on the Development Status of the Chinese Internet published by the China Internet Network Information Centre (CNNIC), as of December 2022, the size of China's short video users was 1.012 billion, an increase of 77.7 million compared with that of December 2021, accounting for 94.8% of the overall number of Internet users [1]. It shows that the short video platform has become the hottest online platform and that both the increase in the transmission rate of short videos and the expansion of the audience have provided strong support for the online marketing of major brands.

At the same time, the short video also has further integration with e-commerce; in June 2022, the short video playback volume of jittery voice increased by 44% year-on-year; users generate commodity consumption through content consumption, and the total commodity transactions brought by short video increased by 161% year-on-year [2]. More and more brands, such as snacks, milk tea, and even many luxury brands, are gradually stationed on various e-commerce, short video, and social platforms. In this context, more and more people joined in. They began to post videos on short video platforms and other social platforms to post graphics, etc., thus gaining many fans and obtaining the opportunity to cooperate with commercial brands. The traditional marketing and publicity model has changed, and many brands choose to cooperate with KOL to increase brand awareness and exposure and consolidate and enhance the brand's reputation. The brand borrows KOL's image and popularity to promote products through recommendations, stimulating the public's desire to buy to promote consumption [3]. At the same time, the use of KOL for word-of-mouth communication is also more credible compared with the brand directly with advertising; KOL is more likely to let consumers feel close to the sense of intimacy and more able to make consumers have the desire to buy. KOL not only plays a guiding role in promoting new products but also in consolidating word-of-mouth for previously existing products [4].

As a medium between the brand and the public, KOL establishes a connection between the brand and the audience, accelerates the speed of information dissemination, and helps the brand consolidate publicity and enhance word of mouth. Therefore, the role of KOL in the KOL marketing model is discursive. The brand ecosystem, on the other hand, influences brand decision-making, and in order for a brand to develop healthily, it is necessary to achieve a coordinated development among the stakeholders affecting the brand, in which the development of brand strategy is an integral part of maintaining the brand ecosystem [5]. After the research concept is clarified, this study will adopt the methods of case study as well as literature analysis, taking CHOCDAY marketing strategy as a case study and how KOL optimises the brand ecology as a theme, to analyse how KOL influences consumers' purchasing behaviours as well as the role of KOL marketing model in optimising the brand ecosystem, as well as the problems and reflections it has.At the same time, this study will also understand how the model can promote the brand to the public by using KOL and then use consumers to stimulate other users to consume, achieve secondary marketing, form a closed business loop, and promote the interaction of the three parties under the brand ecology.

2. Case Study: CHOCDAY

2.1. Brand Introduction

CHOCDAY was founded in 2019, with zero sugar health black chocolate as the brand positioning. It is committed to "do not sweet chocolate" to create a new generation of health-concept chocolate brands. Its purchase channels are divided into online and offline channels; online has been stationed in Tmall, Jingdong, WeChat, and other platforms, and offline is mainly in the middle and high-end chain supermarkets. The brand online only twelve months sales have broken 100 million. In 2020, Double Eleven ranked first in the Tmall chocolate category sales growth, and the whole chocolate category sales third, increasing by 1000% year-on-year [6]. In 2021, it was the champion of Tmall's "618" and "Double 11" dark chocolate sales. According to Taobao's mid-2022 data, in the sales of high-end products in the snacks dark chocolate category, CHOCDAY's main single product rankings have already beaten Dove. Even monthly sales reached twice as much as Dove's, and as of 2022, CHOCDAY has been ranked first in Tmall's dark chocolate category for three consecutive years. CHOCDAY completed two consecutive financing rounds of more than 100 million yuan in the second quarter of 2022. It can be seen that CHOCDAY has become a dark horse in the industry after more than three years of development.

2.2. CHOCDAY Marketing Model

2.2.1. Star KOL

In the face of fierce competition in the chocolate market, the new black chocolate brand CHOCDAY can stand out in the chocolate market, inseparable from the celebrity spokesperson as a KOL to make guidance. Since its establishment, the brand has cleverly used the fans of celebrity KOL to spread and promote the brand so that more people will know and buy CHOCDAY's products because of the celebrity KOL. CHOCDAY's choice of spokesman timing is also just right; in the choice of a well-known actress as a spokesman, the actress is just out of the fan viscosity and the highest degree of activity at this time her spokesman can be more effective to accelerate brand dissemination, to help the brand to promote. The choice of a well-known male celebrity spokesman is also very famous in China and dramatically influences and appeals to the star. Choosing him as a spokesman can also speed up brand communication and increase brand product sales. Just like Pavlov's classic conditioned reflex, initially, the brand CHOCDAY did not have any noteworthy places for the fans of the endorser. Nevertheless, because fans like their own star idol, when their idol endorses the CHOCDAY brand, fans will naturally think of their idol when they see the brand, thus generating the desire to buy its products. In addition, the brand added the star spokesperson's peripheral gift in the product box, which prompted the fans to buy the product more actively. Therefore, using celebrity spokespersons as KOLs to guide the CHOCDAY brand not only boosts the brand's sales but also increases brand exposure and accelerates the speed of brand dissemination.

2.2.2. Influencer KOLs

CHOCDAY also chose to collaborate with several bloggers in various fields to launch publicity and promotion. The brand seeks out different types of KOLs to deliver messages tailored to the audience's different needs and achieve the ultimate promotional goal. Based on this marketing model, KOLs play an important role in consumers' purchasing decisions and impact consumers' purchasing psychology, thus promoting purchasing desire.

During consumers' pre-information search, CHOCDAY takes 0-sugar healthy dark chocolate as its brand positioning to create a different image from other chocolate brands. Last month, the brand released a new product focusing on the ultra-crunchy taste and zero-burden health experience. When the product was launched, the brand found various bloggers to promote it. Based on the brand's positioning, the brand used KOLs in line with the brand's image to accurately place information on the target audience so as to achieve the audience's personalized product seeding. For example, food bloggers promote the products through food production instructional videos, explaining to viewers how to make delicious and low-calorie chocolate desserts. While keeping the video informative and engaging, it also emphasized the low-calorie and healthy features of the brand.

Another example is the lifestyle bloggers, who skillfully integrated the promotion of the products into their daily life sharing. Among them, according to the brand positioning, most of the bloggers focused on sharing their self-disciplined lives, interspersed with healthy and low-calorie snack recommendations to promote the product. These promotion methods, close to people's daily lives, make the audience easier to accept and have a higher degree of conviction. When the content of KOL promotion is in line with the audience's needs, it is more likely to trigger the consumer's motivation to consume. Secondly, according to the unique characteristics of KOL promotion, similar to celebrity KOL, fans may also be induced to buy the product based on their love for the blogger KOL, resulting in followers' purchases.

2.2.3. Online and Offline Activities

In addition to the guidance of KOLs themselves, CHOCDAY's activities around KOLs and co-branding activities with other famous brands have also helped to promote the brand. During the period when famous female celebrities were the spokespersons, CHOCDAY organized blueberry nights, flash mobs, and various forwarding lucky draws for their fans offline. During the period when a famous male celebrity was the spokesperson, CHOCDAY launched the 'Daily Happiness Companion Gift Box' with this celebrity, which included a customized gift for his fans, as well as offline advertisements, online 520 Black Chocolate Confessions Season activities, and various lucky draws. Through these activities, more people followed CHOCDAY's public number, Weibo account, etc., expanding the scope of brand communication. During the activities, the brand got more exposure and increased sales by making fans buy products with celebrity peripheral gifts, share photos with their friends, and tweet with brand topics. In addition to promotion through KOLs found by the brand itself, CHOCDAY has also launched co-branded products with brands such as Anmushi. The brand spokesperson of Anmushi also promoted this product and conducted an online forwarding lottery, which increased CHOCDAY's exposure again. Therefore, the brand in the promotion should not only use the KOL itself for brand promotion but also use the influence of KOL to organize all kinds of activities so that the brand itself gets a broader range of promotions and more significant benefits.

3. KOL Marketing Mode and Brand Ecology

With the development of self-media, different from the previous communication mode, KOL as a medium between the brand and the public significantly shortens the distance between the two and promotes the relationship between the two so that the brand's image expression naturally infiltrates into the audience life [7]. First of all, for the brand side, KOL by video, pictures or text, and other ways to introduce the brand products. The fans to comment on their published content forwarding can increase the heat for its content. When the heat reaches a certain level, the platform will distribute a more considerable amount of traffic for the content to achieve the effect of cell fission-like propagation, which can help the brand to get more exposure, increase awareness, and also let the public know more about the brand to promote the purchase and increase brand sales [8]. As Qi Yu argues, star-type KOL, relying on its large fan base, can maximize the scope of the brand's dissemination and increase attention to the brand [9]. Grassroots-type KOLs post graphics closer to the public's life, which can easily make the public less wary of commercial advertisements, so the content they post is also more likely to achieve the effect of brand communication [9].

Secondly, for consumers, KOLs convey information through the introduction of brand products so that consumers can more directly access the information they need to decide whether to buy or not. As Li Jie and Chen Sisi said, KOLs have a certain degree of professionalism and credibility in their respective fields [8]. By having them deliver brand information directly to the audience, they can effectively deliver brand information, establish a brand image, and quickly enhance brand reputation [8].

In addition, the emergence of KOL marketing allows the audience's identity to change according to the media scenario [10]. For example, if a KOL produces a video or graphic in a specific scenario provided by a brand, it is likely that after the public receives this information, they will be able to make a purchase because of these posts.

Suppose consumers have a good sense of shopping experience. In that case, they may even imitate the photos posted by bloggers and eventually post graphics of their purchase experience on their social media, thus providing more brand promotion and marketing [10]. The formation of KOL-driven consumers and consumption and then drive the consumption model. It optimizes the brand ecosystem, promotes the interaction between the three parties, and forms a benign interaction.

To sum up, KOL acts as a bridge between the brand and the public, conveying the brand information to the public, increasing the public's awareness of the brand, establishing the brand image, and enhancing the brand's exposure, popularity, and reputation. At the same time, KOLs also increase their heat and attract traffic by posting videos, graphics, and other information about the brand. In addition, consumers can also buy the right products through KOL's promotion. Through this three-way interaction, the brand ecosystem is also further optimized.

3.1. Current Problems and Reflection

KOL promotion is a new and fan-centered publicity mode. Due to its specificity, it is difficult to avoid bringing negative impacts when promoting. For example, to a large extent, it will lead to impulsive consumption. Impulsive purchasing aims at the sudden consumption behavior produced by the buyer under the influence of external factors, such as online or offline advertising campaigns, which may cause the desire to buy, thus inducing unexpected consumption [11]. First of all, in terms of celebrity KOL, fans are likely to purchase products out of their love for the idol after seeing the celebrity endorsement to express their support for the idol's cooperation with the brand in this way. However, not all endorsed products can precisely meet the current needs of fans. In this case, it leads to an unplanned consumption.

There is another example of a promotional video of a Chinese blogger on CHOCDAY, in which the blogger shares her tips on maintaining weight and keeping fit. By recommending low-calorie snacks, the video introduces CHOCDAY's product, including its flavor, performance, and packaging. The video's direction for the product promotion targeted the audience of women who are in the body management period, making the promotion more relevant. The brand utilizes the target audience's specific psychology of looking for healthy and low-calorie food to promote the product, making it easy for the audience to substitute themselves while watching the video and thus consume on impulse. The blogger also added scenarios in the video to describe her own experience. For example, she mentioned that she usually carries a pack of chocolate with her when she goes out to satisfy her cravings during her diet without worrying about excessive calorie intake. This scenario-based description provides a clearer picture for the audience, combining the product with the life scene to cause cognitive connection and resonance, further stimulating the audience's desire to buy [12]. In this case, it is easy to lead to some unnecessary consumption. The content of the KOL video attracts consumers, so they buy the product. However, after the consumption, they may find that the product fails to solve their fundamental needs. In this way, consumers lose their money on the one hand and may also have a negative attitude towards the product itself.

Based on the above analysis, the KOL marketing model plays different roles among brands, KOLs, and audiences. From both marketing and social perspectives, the model is contradictory, which promotes the positive interaction between the three parties in the brand ecological business closed loop but also has specific problems at the same time. The intervention of KOL makes the role of the audience blurred. People are switching between passively receiving and actively disseminating information. However, the audience's ability to think independently is not necessarily mature [7]. In addition, as KOLs help brands break through the distance between them and the audiences, such as the scene depictions in the promotions mentioned above, audiences are more likely to be influenced by KOLs, leading to impulsive consumption and other such problems. Therefore, audiences need to improve their judgment and awareness, which can help minimize such negative impacts and prevent them from falling into marketing traps as much as possible.

4. Conclusion

As today's active internet and We Media provide a more personalized and diversified platform for people, the original communication mode changed dramatically. The emergence of KOL makes the relationship between the brand and the public no longer limited to the communicator and the communicated.

The paper analyzes the marketing model of CHOCDAY as an example, restoring the three marketing models adopted by the brand, celebrity KOLs, influencer KOLs, and the online and offline activities and co-branding cooperation around the KOLs. Also, the paper provides evidence from various aspects that KOLs have enhanced the positive interaction between the brand and the audience as a medium. The KOL marketing model forms a closed business loop that increases the brand's exposure, stabilizes the brand image, and provides a new way for the audience to obtain and distribute information. Driven by this marketing model, brands choose KOLs; KOLs promote to their target audience, who then post information on their social media, which drives new audience and feeds back to the brand, thus creating a loop. It promotes three parties' interaction and optimizes the brand ecosystem. However, as mentioned above, it is difficult to avoid some negative impacts in the process of KOL promotion, such as triggering consumers to follow the purchase trend that leads to impulse consumption. After social information dissemination has become more fragmented, the audience must improve their judgment when processing and receiving information to minimize external factors' influence on purchasing behavior.

In today's Internet era dominated by We Media, KOL marketing is undoubtedly a dominant form of promotion that is debatable and worthy of more in-depth study. At present, the paper has yet to launch a superficial investigation of KOL marketing based on the analysis of the case study of CHOCODAY's marketing model, which lacks a more comprehensive analysis and still has many deficiencies. In the case study process, other marketing modes, such as personalized and scenario-based marketing, are flexibly used together with KOL marketing, which will be a topic worth discussing from the marketing point of view.

Acknowledgements

All the authors contributed equally and their name were listed in alphabetical order.