Yuu's life as a student, living alone in a dorm away from home, is drawing to a close, and graduation is fast approaching. On the way home from the graduation ceremony, his stepmother, Marina, runs up to him with a smile, and his hidden feelings begin to stir once again. That night, after drinking too much to celebrate their graduation, Yuu drives Marina to a hotel... He tries to contain his emotions and leave the room, but Marina says, "I'll give you a graduation gift from me, so please accept it."