Banzai, whose full name is Wan Sui, is a wealthy transfer student who initially changed schools to avoid attention linked to his family's financial status. His economic privilege surfaces through habits like relying on chauffeur-driven transportation.

He develops romantic feelings for Shi Miao, influencing his group interactions. Banzai acts protectively toward her, even abandoning his chauffeur upon being spotted by Shi Miao to avoid seeming overly dependent on wealth, marking a significant step in adapting to ordinary social dynamics.

His character evolution involves gradual integration into group activities despite initial elitism. He reluctantly participates in a public bath visit after getting splashed with mud. Though intimidated, he eventually adopts group behaviors like mimicking poses. This experience culminates in a traumatic sauna competition with Shi Fen, resulting in a lasting aversion to public baths.

Banzai forms friendships, notably with Shi Fen and Kai Xin. A key moment occurs helping Shi Fen declutter his room. Banzai insists on discarding items, showing practicality, yet respects sentimental value upon seeing the onyx stone he gifted—though Shi Fen discards it casually. Later, when Banzai discards shoes after learning they are cheap imitations, Shi Fen shares one shoe in a gesture of camaraderie, causing mutual inconvenience.

His observational skills are evident when he notices Shi Fen's concealed fear during a roller coaster ride, contrasting Shi Miao's nostalgic perception of her brother's bravery. Banzai also participates in schemes, like confiscating Kai Xin's phone to enforce study focus, highlighting his role in group interventions.

Banzai's development includes embracing modest experiences, such as cycling to school on a bike with training wheels gifted by Miao Miao. This choice reflects his growing preference for self-reliance over luxury, puzzling his chauffeur. His journey depicts a shift from aristocratic isolation to valuing friendships and ordinary adolescent experiences.