Kokoro is a beautiful, timid and quiet girl who is always alone at school, loves books and always hangs out in the library. One day, when her homeroom teacher's lewd gaze stirs up lewd fantasies, she is attacked by him when she is alone with him in the library. She resists a little, but she is violated. Unable to forget the pleasure she felt at that moment, she calls her homeroom teacher and kisses him as if she is asking for it. Since then, the days of vulgar sex between the middle-aged teacher and the timid female student have begun.