Mary is frustrated with her husband, who rarely has sex with her because he is so busy. At the hospital, she is diagnosed with a low sperm count, and although there is still a chance of pregnancy, it is difficult unless a miracle occurs. One day, her husband's father comes to Tokyo to visit and stays. As her father-in-law is also looking forward to his grandchild, he is reluctant to reveal his worries. By chance, he finds out about his son's situation and gives Mary an aphrodisiac. He asks her if she is really satisfied with sex with his son. He says he will take responsibility as a parent and rapes Mary, cumming inside her. Mary becomes aroused by her father-in-law's repeated aphrodisiac attacks, and begins to desire her father-in-law instead of her husband.