The mother-in-law has a father who remarried and lives together with a woman who is not much older than herself. She feels complicated about it, and the family's unity, the kotatsu, and the skin-to-skin contact. There is an arousal with the body craving for a woman who is too young to be called mother. The other party shares the same feelings and secretly flirts under the kotatsu. In the end, the two couldn't help but be pressed against each other by the father.