Kitamura Kaori serves as the president of her school's tennis club. A tennis tournament is approaching, yet one of her juniors, Sasaki Ami, has recently been absent from all training sessions. Concerned, Kaori decides to visit her. Upon arriving at Ami's residence, Kaori rings the doorbell, but Ami is just about to engage in fun with a man. Because she dislikes presidents—having never managed to defeat Kaori—Ami lets her in, and Kaori witnesses her sleeping with a man. Overwhelmed, Kaori asks what is going on, but suddenly the man moves toward her. What is happening?