After his father's remarriage, Yui, who is the same age as him, becomes his stepmother. Teasingly, she flaunts her seductive figure and repeatedly provokes him with sensual advances. The son finds himself emotionally stirred by her behavior, picking up a pubic hair she dropped and masturbating in his room while sniffing it. Suddenly, Yui appears and catches him—flustered, he confesses his attraction, admitting how drawn he is to her very pubic hair.