Worried about her good-for-nothing son Kyohei's poor lifestyle, mother Natsumi comes across a line in a book stating "virgins tend to have bad habits," making her suspicious about whether her son is truly a virgin. This small doubt spirals into a forbidden incestuous affair. To test if Kyohei is still a virgin, she begins with a blowjob, but things quickly escalate into creampie sex. A sensual milf abuses her son's body as her plaything, grinding her big ass wildly in ecstasy. What started as an attempt to correct her son's behavior twists into a taboo relationship.