61-year-old Michiko married a man she met at a matchmaking event, and half a year has passed since she settled into her new life. However, she struggles to bond with Seiji, her husband's adult son from a previous relationship, and their relationship remains strained. One day, Michiko discovers that her stepson Seiji has a fetish for mature women. Worried about his future, she scolds him for his perverse desires—but her words only serve to excite him further. Soon, Michiko's long-unfulfilled body responds to Seiji's youthful, intense advances, and on her sixtieth birthday, she collapses into unconscious pleasure.