Rinta leaves his tiny rural village and moves to Tokyo to attend a large university. Shy and bookish, he joins the literature club in search of a quiet campus life there he meets the club's most famous member, the upperclassman known to everyone as Fumi-san. She is widely regarded as the most beautiful girl on campus, with a soft, elegant aura that draws crowds of admirers to the clubroom every day. After a drinking party with club members, Rinta volunteers to walk Fumi-san home. He believes he has safely delivered her to her door, but the moment he turns to leave she drops her demure facade. She forcefully pulls him into her bed and challenges him to resist her, whispering that she wonders how long he can keep being a good person.

Thus begins a forbidden and psychologically charged campus life. Fumi-san subjects Rinta to a series of escalating seductions and manipulations, including a humiliating reenactment of the Sleeping Beauty game. She teases him, blackmails him with incriminating photos, and systematically dismantles his carefully constructed persona of a harmless, principled young man. Rinta, who has never been in a relationship and is terrified of sex, desperately clings to his "good person" mask while his body betrays him. Fumi-san presses him to admit that he is merely a coward hiding behind morality, and she offers him excuses to surrender: that she is too seductive, that no man could resist. The story explores the tension between Rinta's genuine desire to be a decent person and the raw, animal instincts that Fumi-san awakens in him.

As the narrative progresses, the focus shifts from pure psychological warfare to a deeper mystery. A summer camp arc introduces a new dimension to the relationship, and the annual fireworks festival reveals the existence of a man from Fumi-san's past: Iori. He is a charismatic, seemingly kind figure who once had a profound influence on Fumi-san, changing her in ways that Rinta cannot yet understand. Iori returns from studying abroad and begins to interact with both Rinta and a club member named Ki, gradually drawing closer to the latter. After Iori's return, Fumi-san's seductions become even more intense, as if something inside her has been unleashed. Meanwhile, Rinta becomes determined to uncover the truth about what made Fumi-san the woman she is today. The central conflict evolves into a triangle of obsession, secrets, and the question of whether Rinta can ever truly reach the real Fumi-san behind her mask of untouchable allure.