Mariko serves as an officer in the PTA of the middle school her eldest son attends. One day, at the president's suggestion, they decide to hold a wrap-up party for the school festival, including the homeroom teacher. The mood heats up at the izakaya during the first round, and then they move on to karaoke for the second round. Amidst this, Mariko, frustrated with her desires, sets her sights on her son's homeroom teacher. Using her experience as an older woman and her maternal instincts, she begins a close seduction. Eventually, the two fall into an affair...
