Yamato Nagaura is an art teacher at a school where he is systematically bullied by his fellow teachers and treated with contempt by his students. His gentle personality makes him an easy target, and the daily humiliation pushes him to the brink of mental collapse. He begins hallucinating that even those who try to comfort him are mocking him, and he hides his suffering from his wife, Aya, who remains unaware of the depths of his despair at work.

One day, after a video of him nearly striking a student is circulated among the staff, Nagaura reaches his limit and heads to the rooftop to take his own life. He is stopped by Sawaki Nao, a younger female teacher who admires him. She confesses her feelings, kisses him, and they sleep together. Nagaura feels both gratitude and deep regret. Although he tries to maintain normalcy at home, the guilt and emotional confusion persist. That night when he embraces Aya, he sees Nao's face instead of his wife's, and the intimacy becomes a source of anguish rather than comfort.

The affair deepens as Nagaura and Nao begin working together on a parent complaint case, and they continue their secret encounters at school. Their hidden relationship is nearly discovered when Aya makes an unannounced visit to the school, but a quick cover-up preserves the secret for the moment. However, a female student named Moushin appears with a video recording of Nagaura's earlier violent outburst and uses it to blackmail him into a sexual relationship. Nagaura complies out of fear but finds the encounter disturbing and stops halfway. Moushin reveals that her actions stem from resentment toward her mother, who abandoned her own principles. After confessing this to Nagaura, she deletes the video and decides to reconcile with her mother.

Despite this resolution, Nagaura is overwhelmed by the realization that he has become a teacher unfit for his role. He resolves to confess everything—the bullying he has endured and his affair with Nao—to the vice principal. But before he can do so, a video of him and Nao having sex is leaked to every computer in the faculty room. The person responsible is not Moushin, who had deleted her copy, but someone else among the staff. The secret is now exposed to the entire school, and the consequences loom.

The story is set in a Japanese school, where the staff room and the art room become the stage for a downward spiral driven by workplace bullying, emotional neglect, and the desperate choices that arise from isolation. The narrative traces Nagaura's collapse from a bullied teacher into a man trapped by his own survival instincts, with the affair acting as both a lifeline and a noose. The characters around him—the oblivious wife, the devoted but complicit junior teacher, and the calculating student—each reflect different facets of the pressures bearing down on him. The story is driven by the tension between the desire for escape and the inescapable consequences of the paths taken to find it.