At the age of 15, Isoyama Kaori (played by Narumi Riko), a girl who has practiced kendo since childhood, participated in the national junior high school competition. She had never suffered a defeat before, but she unexpectedly lost to the unknown girl Sanae Komoto (played by Kitano Kii) from Tomatsu Academy. Kaori was upset about this, and in order to defeat Sanae, she volunteered to apply for the high school department of Tomatsu Academy. Unlike the serious and ancient Kaori, Sanae is a cheerful and optimistic cute girl. Even her parents' divorce did not have much impact on her body and mind. Although Kaori regarded her as an old enemy who must be defeated, Sanae did not take it seriously at all, but made friends with Kaori. The two girls with completely different personalities influenced each other and infected each other with their own lives. They even walked into the venue of the national summer competition side by side... This film is adapted from the novel of the same name by Tetsuya Takada.