Maki and Teruna are female college students and close roommates, yet they harbor a sense of rivalry toward one another. One night, when Teruna returned home late, she found Maki in the middle of having sex with her boyfriend, Masuda. Aroused by the scene, Teruna gave in to the urge to masturbate. The next morning, while Teruna was sleeping alone, a burglar named Kuroda broke into the apartment...