Aina Yoshiwara is a first-year student at Oumi Women’s University who initially joins the Tinkerbell tennis club hoping for an easy path to romance and friendship. To stand out, she adopts a flashy persona known as “Cakey,” wearing a blonde wig, heavy makeup, and gaudy clothing. This backfires, leading to bullying and isolation from her seniors. Her natural appearance features short dark blue hair and a gentle, subdued demeanor. During the Miss Izu Contest, a breakdown leads Iori Kitahara and Kouhei Imamura to defend her, giving her the courage to leave Tinkerbell and join the Peekaboo diving club. There, she gradually abandons the Cakey identity, forms genuine friendships, and discovers a passion for scuba diving. Within the club’s rowdy, often nude atmosphere of heavy drinking and partying, Aina frequently acts as a sensible voice of reason, chastising inappropriate behavior. However, alcohol unleashes a wild, uninhibited side, causing her to become reckless and even attempt to remove Iori’s underwear; intoxication also triggers her native Kitakyushu dialect. She harbors deep insecurities about her small bust size, envying bustier women and reading books on bust enhancement. Having grown up helping with her family’s farm and business, she is a skilled driver who holds a manual transmission license and can operate a tractor, skills she uses during club trips. Aina develops romantic feelings for Iori after his defense of her, leading to an unrequited confession. Later, she accepts a romantic confession from Kouhei Imamura. Her journey centers on overcoming social anxiety, embracing her authentic self, and finding belonging within Peekaboo, where she transitions from an isolated outcast to a valued member who balances the group’s chaos with grounded pragmatism.