Kaori Hanazono is a wealthy heiress and well-regarded, academically accomplished student at Wakaba Academy who holds influence among a group of peers. Despite her privileged status from her family's corporate ownership, she maintains a humble demeanor and seeks genuine connections, though her family's prominence can create distance. She becomes suspicious of Hibari Ōzora's gender identity after observing physical traits she interprets as masculine, including a flat chest, and overhearing Kōsaku Sakamoto call Hibari a "pervert." Driven to expose Hibari, she orchestrates schemes. She hires delinquents to forcibly undress Hibari, but Hibari defends herself. Later, Kaori pressures Hibari to disrobe during a school health checkup, aiming for verification; this fails when Tsubame Ōzora impersonates Hibari and undergoes the exam.

Kaori's persistent efforts extend to swim class and a school-sponsored summer camp, where she and her group probe for evidence Hibari was assigned male at birth. Hibari consistently evades these attempts through caution and cleverness. Kaori never confirms her suspicions or reveals Hibari's identity. Her interactions are primarily defined by this ongoing campaign against Hibari, driven by jealousy over Hibari's popularity and status as the school idol. Her motivations, personal relationships, and role remain centered on this antagonistic dynamic throughout the series.