Kyōka Kanejō, a wealthy transfer student returning from America, joins the main characters' class in their second year of high school. Driven by perfectionism, she excels in modeling, cooking, sports, and academics, frequently asserting her superiority. Finishing as runner-up to Yamada in the school beauty pageant ignites a fierce rivalry, fueling Kyōka's obsessive drive to surpass and undermine her. This competition leads Kyōka to declare her intent to steal Yamada's boyfriend, Takashi Kosuda, as part of her campaign.

Kyōka harbors a significant complex concerning her older brother, Keiichi Kanejō, a Harvard Business School student. She maintains a secret room filled with his pictures and personal items, revealing an extreme, almost possessive familial fixation. Her actions include covertly eliminating Keiichi's potential romantic interests to maintain his attention and virgin status. When Keiichi visits Japan and shows interest in Yamada due to her lack of immediate infatuation, Kyōka's protectiveness and jealousy intensify.

She employs manipulative tactics to interfere in others' relationships, such as impersonating medical staff during a hospital incident to disrupt moments between Yamada and Kosuda. Kyōka's own Eros Deity manifests as a noblewoman with a fan, reflecting her self-perceived elegance and superiority. Despite persistent efforts to sabotage Yamada's romantic pursuits and control her brother's love life, Kyōka's schemes ultimately fail to secure a lasting romantic connection for herself or permanently damage Yamada's relationship with Kosuda by the series' conclusion.