While playing at his best friend Shogo's house, Takeshi sees a beautiful woman he doesn't recognize. He thought it strange that she was too beautiful to be Shogo's older sister. The next day, Takeshi is left waiting at home for Shogo, who forgot to submit his report, when he encounters the beautiful lady. Takeshi, who is being seduced by his girlfriend's older sister, is shocked when he feels something hard in her older sister's lower body.