Nina raised her son alone. Her son also found a job, and she suggested he live by himself, but he wouldn't leave. She occasionally invites him on a hot spring trip. During the trip, her son suddenly confesses that he has always liked his mother and has felt this way since he was small. As her son pours out his feelings, the mother gradually takes it seriously. Feeling sorry for her son, who is still a virgin because of her... she thought it was just a bit of maternal love... Although it was supposed to be just once, she gasps and feels intense pleasure. The taboo story of repeated incest between mother and son.
