Spring of the 1st year in high school. Kumiko Oumae who had belonged to the concert band in her junior high school years, visited the high school concert band with her classmates Hazuki Katou and Sapphire Kawashima.
And there, she happened to see Reina Kousaka, who was a Kumiko’s classmate in her junior high. While Hazuki and Sapphire decided to join the band soon, Kumiko hesitated to do so.
Reina reminded her about a certain experience at a tournaments of concert band in junior high school. They will find out precious things through their activities in the concert band. This is a story of the girls' youthful life, filled with their passion and purity.