Emiko (RYU), who separated from her husband a year ago, lives with her son Ryusuke. One night, Ryusuke sees his mother masturbating in the room and develops strange feelings towards her. Ryusuke, who can’t hide his excitement when he sees his mother’s sexy appearance, confesses that to her and urges her to have a relationship. Although the mother is confused, she agrees that “if it is sex education …” and teaches her son about sex education with her own body.