Satoru and his wife, both working full-time, struggle with trying to conceive, leading his wife to return to her parents' home. However, she constantly makes excuses to avoid intimacy, causing their relationship to deteriorate until they stop having sex altogether. Concerned about the situation, his mother-in-law, Chisato Shoda, takes notice. One night, Satoru sneaks into Chisato's room and begins touching her body. When Chisato wakes up, she's confused, but then says, "You've been holding back... I'll take responsibility for my daughter's selfishness," and the story takes a new, forbidden turn.