Yuri Kashiwaga was as soon as called a brilliant pianist. One day, she goes back to her hometown in Goto Islands from Tokyo. There, she begins to work as a momentary educator at a middle school and expert for the school carolers. The chorus aims to take part at a competitors. Yuri provides the participants of the carolers members a job. She instructs them to compose a letter with the title of "To myself 15 years later on." The 15-year-old young boys and ladies cover their keys and also worries.