18+ Toritsu Eros Gakuen

Kiri Ikeda is a member of her school's swim team. One day after practice, she heads to the locker room only to find her kouhai, Rumi getting gangbanged by a bunch of guys. As she watches through the crack in the door, Kiri starts to get turned on but suddenly remembers her own questionable past and runs to the showers to clear her mind. One of the male members in the gangbang sees her leave and follows her...

(Source: BakaBT)