Ayano Hamaura

The Kanto area and Kansai area are in secret tug of war. Descendants of ninja from Kansai harass Kanto area. One day, 4 female high school students from Tokyo transfer to a new school. They are descendants of ninja who are sent to protect Tokyo.

Yuri Kashiwaga was once known as a genius pianist. One day, she returns to her hometown in Goto Islands from Tokyo. There, she begins to work as a temporary teacher at a middle school and advisor for the school chorus. The chorus aims to take part at a competition. Yuri gives the members of the chorus members an assignment. She instructs them to write a letter with the title of “To myself 15 years later.” The 15-year-old boys and girls write about their secrets and worries.