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.

A young piano prodigy, Yuri Kashiwagi, returns to her hometown after several years and joins a middle school to mentor the choir group.