Koshiro is recovering from breaking up with his girlfriend. On his way to work on the train, he first meets Nanoka while returning a name tag that she dropped as she was trying to exit the train. After returning to his house from work, he finds out from his father that his sister, whose face he can no longer remember, will be moving into their house for an easier commute to her school. The next day his girlfriend visits him during lunch break to get back the key to her house. At the end of the work day, a customer gives Koshiro and his boss two tickets to the theme park next door. Upon leaving their work place, Koshiro meets Nanoka again and spends the rest of the day at theme park with her; they console each other on their love lives. Their father appears at the end of the day to pick Nanoka up, revealing to both that they are siblings.