Kana and her husband still get along well, and they have sex quite often at night considering their age. However, her husband has become weaker recently, and Kana has become a little frustrated. Her son has been watching them and knows that his father has become weaker and his mother is frustrated. One day, when her son comes home from work, he finds Kana sleeping in the living room with her breasts exposed. He approaches her, rubs her breasts, and plays with her crotch. Kana wakes up and scolds her son. However, her son can no longer hold himself back and pushes her down. From that day on, Kana, who is no longer satisfied with her husband and a vibrator, accepts her son...