Michiko Uchimura, a 45-year-old housewife. Her husband frequently travels for work, leaving him home only occasionally. Her son is also busy with school and part-time jobs, rarely spending time at home. As a result, she finds herself increasingly alone each day. One day, she called out to her son, who had the day off from his part-time job, only to discover him in the middle of masturbating. Worse, he was calling out her name. Though initially shocked, she found herself feeling affectionate toward her son. She began fantasizing about having sex with him and ended up masturbating herself. Mother and son, masturbating separately on opposite sides of a sliding door. But then, she realizes—he had actually been watching her all along.