One night, a couple's intimate act is witnessed by their son and daughter. Then, from the daughter Yuzuki's words 'Dad, is sex really pleasurable?', the Kanou family's twisted sex education begins. In the bathroom, they teach fellatio, and in the children's room, the mother teaches the son, and the father teaches the daughter individually. Then, under the watchful eyes of their parents, the siblings practice what they've learned…
