Tsukushi, who enjoys photography. One day, he accidentally captures a panty shot of Matsui, the class idol. Having obtained the panty shot, Tsukushi becomes obsessed with Matsui's underwear and starts taking pictures of it or masturbating without regard for others' presence. Matsui noticed Yuzuki's behavior and snapped a picture of her underwear, from which the two began their forbidden relationship. They both got into lesbianism, kissing and getting physical with each other in school, getting each other excited.
