A mother who stole her son's virginity

The Yamashita family is a judo family that practices every day. At first glance, the family appears to be harmonious, but Yayoi secretly seeks funds to run the dojo on the condition that he enters into a mistress relationship with his brother-in-law. One day, Tsuyoshi, a virgin, expresses his hidden feelings for his mother for the first time when she asks him about his lack of practice. Yayoi takes Tsuyoshi's brushes in the rehearsal room because she wants to make him a full-fledged man, but she gradually begins to love her son as a woman and worries about her relationship with her brother-in-law...