Naho, a married 31-year-old woman, embarks on an affair during a train ride that marks the beginning of her infidelity. Her visible nervousness and the way she touches her H-cup breasts convey a mix of humiliation and arousal. As she begins desiring a man who isn't her husband, the story gradually unfolds her growing romantic feelings. This is the record of her illicit journey, walking the path of betrayal—a work depicting the start of a new romance.