Mother Kyoko is deeply troubled by her son Keisuke's irresponsible behavior. When her nephew Shinkurou tells her that Keisuke is still a virgin and that's why he acts so undisciplined, she decides to personally provide her son with sex education using her own body. This decision stems from a mother's love and her strong desire to raise her child honestly. Kyoko's actions are more than just education—they are the embodiment of love and responsibility.