Emi lost her husband last year and began living alone. Recently, her daughter and son-in-law invited her to move in with them, and she has been living with the couple for the past three months. She's happy to be living with her daughter again and has no complaints about the arrangement. However, she still feels uneasy having a young man in the house and finds herself increasingly aware of his presence. Lately, she's become aroused watching her daughter and son-in-law's nighttime activities, leading her to masturbate frequently. One day, her son-in-law catches her in the act. Later, he approaches her and says, "Let me give you a massage." Emi accepts his offer. As her oil-slicked buttocks tremble under his hands, he whispers, "Why don't we do something more pleasurable than just a massage?" Yielding to his temptation, Emi gives in, and their forbidden affair begins.