Midareuchi Episode 1

Kitamura Kaori is the president of her school's tennis club. There's a tennis tournament coming up soon, but one of her juniors, Sasaki Ami, has been missing from all of the training sessions lately. Out of concern, Kaori wants to pay her a visit. When she arrives at Ami's, Kaori rings her doorbell, but Ami is just about to have fun with a man. She doesn't like the presidents since she's never been able to beat her, so Ami lets Kaori in and Kaori sees her sleeping with a man. Kaori is overwhelmed and asks what that is about, but suddenly the man makes his way in her direction. What is happening?