Yumi, who preceded her husband, raised her son Nobuyuki by herself. It seems that her son has made her recently, and she secretly watches over her with mixed feelings, but one day she confesses her worries that she cannot be satisfied with premature ejaculation. Yumi who was worried decided to give sexual training to her son. Nobuyuki's premature ejaculation is not fixed, but Yumi uses her own body to teach her son sex.