High school student Kouji finds himself attracted to older women. Sadly for him, though, he attends an all boys' school where the female teachers are old and ugly; it also doesn't help that his 38-year-old mother is beautiful, with a great body to boot. As a result, Kouji often finds himself thinking about her.
One day, when Kouji's report card arrives, his mother discovers that he's gotten a "D" in Health Education. Worried that her son might not be receiving the proper knowledge—or, even worse, that he may become a sex offender in the future—she decides to take matters into her own hands and teach Kouji the ins and outs of intimacy.