It's been a month since her daughter and son-in-law started living together to save up for a house, but Yumi has one complaint. She can hear their nightly lovemaking in her room. Unable to contain her excitement, she masturbates, but her body just wants to be violated... Realizing that her stepson, Ataru, has feelings for her that go beyond those of a father and son, Yumi takes every opportunity to stimulate his lust. However, when Ataru refuses to take the final step, Yumi's body's throbbing reaches its limit...