Rimu, who will graduate next year, has only kissed her boyfriend Yuta so far, never progressing further. The two had promised to wait until they became adults before taking their relationship further. When Rimu visits Yuta's house, she meets his father, who treats her with gentle, almost fatherly affection. One day, after trains stop running and she can't go home, Rimu suddenly has to stay the night. The next morning, while Yuta is away, Tohru slips an aphrodisiac into Rimu's drink.