Kayo Yamaguchi (43) discovers one day that her son has a habit of peeping, causing her to worry he might be behind a recent string of voyeurism incidents. Her fears prove unfounded, but seizing the opportunity, she decides to properly educate him about sex. She bares her own body and carefully explains the mechanics of a woman's anatomy. However, her son's interest deepens beyond expectation, and a new relationship begins to unfold...