Banzai, formally known as Wan Sui, is a wealthy transfer student who deliberately changes schools to escape the attention surrounding his family's affluence. Driven by a desire for an ordinary life experience, free from privilege and expectation, he forms close bonds with Shi Fen and Kai Xin, integrating into their social circle despite his initial aim to remain inconspicuous.

He develops an affection for Shi Fen's younger sister, Shi Miao, making various attempts to gain her notice, though these feelings are largely unreciprocated. His position as an outsider to the siblings' relationship occasionally provides perspective on their dynamic.

His younger brother, Wan Xing, periodically appears to monitor him, reflecting familial obligations. Initially embodying stereotypical wealthy mannerisms, Wan Xing is gradually influenced by Banzai's lifestyle and friendships, showing subtle shifts toward a more relaxed demeanor through ongoing exposure to Shi Fen and Kai Xin.

Banzai's development involves navigating the conflict between his quest for normalcy and unavoidable aspects of his identity, such as participating in family financial matters. His involvement in group activities—including military training exercises, auctions, and communal meals—highlights his adaptability and growing comfort within the friend group, despite occasional reminders of the economic disparity between him and his peers.