The storyline centers around (played by Sora Aoi), an impish, magnetic high school senior navigating her final year before graduation. Rather than focusing solely on exams, Tsumugi harbors a profound infatuation with her married teacher, Shinichi Katagiri (Takashi Naha).
Fueled not just by adolescent desire but by a characteristically bold and "liberal" attitude toward sex, Tsumugi decides to take matters into her own hands. She directly confronts Katagiri, forcing herself into his home and initiating a physical relationship with him. Complicating the story further are two key events: Katagiri is also a cheating husband, with his wife away awaiting the birth of their child, which throws his actions into sharp moral contrast. Simultaneously, as Tsumugi's affair with her teacher escalates, she begins to develop genuine feelings for a fellow student, , putting her on a collision course between raw desire and genuine romantic connection. Tsumugi -2004-