Struggling students Tanaka and Yamada stay overnight at their homeroom teacher's house to study. Tanaka becomes infatuated with the teacher's beautiful wife, Sayuri, and aggressively seeks to get close to her. Initially resisting, Sayuri gradually succumbs to Tanaka's bold yet tender advances, awakening her own desires. Yamada witnesses the affair, sparking a tense, obsessive romantic entanglement between the two boys. As Sayuri embraces her growing passion, the intensity of their relationships escalates, leading to new and complex developments in their illicit love triangle.