Ahead of graduation next year, her boyfriend Yuta has kissed her, but she hasn't done so yet. He had promised that his physical relationship would only begin as an adult. When Rimu comes to her boyfriend's house to play, she meets Yuuta's father and is treated kindly as if she were his daughter. On that day, the train stops and Rimu can't go home, so he has to stay overnight in a hurry. The next day, in Yuta's absence, Toru gives Rimu an aphrodisiac.