Yumiko lives with her husband and son. Her son is a university student and seems to be busy with his part-time job, so she worries about his studies and health. One day, her son sees Yumiko masturbating with vegetables in the kitchen. Her son gets an erection from his mother's lewd behavior. A few days later, her son comes home while Yumiko is taking a nap in the living room. Seeing his mother's panties, he becomes aroused and strokes his penis next to her as she sleeps, eventually ejaculating. Yumiko notices this and scolds him, saying, "You should do that with a woman other than your mother," but he pushes her down and says, "I won't be able to hold myself back anymore if I see your erotic, perverted masturbation!"