While playing at his best friend Shogo's house, Takeshi sees a beautiful woman he doesn't recognize. He wonders why she's too beautiful to be Shogo's older sister. The next day, Takeshi is waiting for Shogo at home because he forgot to submit his report, and he bumps into the beautiful older sister. After being flirted with by the older sister, Takeshi is shocked to feel something hard on her lower body.