A widowed mother named Kaori Yoshimura lives alone after her husband passes away. Her daughter decides to move back home to help take care of her, but things aren't going well for the son-in-law. He finds himself constantly fantasizing about his beautiful stepmother. One day, he can't resist any longer and embraces her while she's getting ready for the bath. Despite protesting at first, Kaori's body reacts instinctively, and she starts dripping with pleasure. As they continue their secret encounters, they are eventually caught by the daughter...