One night, a married couple's intimate moment is accidentally witnessed by their son and daughter. From this incident, the twisted sex education at the Kano household begins. When daughter Yuzuki innocently asks, "Dad, is sex enjoyable?", it sparks a series of sexual lessons within the family. In the bathroom, fellatio techniques are taught, while in the children's room, the mother privately instructs the son and the father individually guides the daughter in sex. Under the parents' watchful eyes, the siblings put their newfound knowledge into practice. Amidst this unusual dynamic, the family's bonds and distortions are gradually revealed.