It's been a year since her son Jun stopped going to school... Unlike her optimistic husband, Yui, his Yui, tries to understand Jun's feelings. She notices that Jun has recently shown interest in Yui's body. When she hears his story, she learns that the reason he stopped going to school was because people around him made fun of him for being a virgin. Strangely enough, Yui is sexually frustrated, and somewhere in Kokoro she is conscious of her son's penis, so she begins to gently teach her son how to lose his virginity. She shows her son every inch of her beautiful body, how to kiss, the feel of her breasts, and how to penetrate him... A beautiful mother gives him a gentle and loving sex education.