While her mother-in-law goes on a trip to a hot spring with a friend, Yuko ends up caring for her father-in-law. Although she does her best as a caregiver, her father-in-law, who has had his eye on Yuko's body for some time, sexually harasses her. He ignores Yuko's confusion and his sexual harassment becomes more and more extreme, and they end up having a relationship. Although she feels guilty towards her husband and mother-in-law, she becomes her father-in-law's toy.