When in junior high Yamato Yuuta ever being asked to going out by Kobayashi Karin if they win their third year and last concert band concours. Yuuta inquire, how then if they end up losing, and Karin response that she will attend the same high school with Yuuta and won in the next concours so they can go out. In the end, though, they lost that last competition. Yuuta then went into Higashi Ikeda to join the concert band—as promise—along with Karin, and four of their friends also: Haruka, Io, Mikoto, and Yukki. They intend to avenge their defeat in the past, targeting for All-Japan Band Competition. Unfortunately, for some unknown reason, when they shout out that spirit, everyone in the club say: it would be better for them to not enter any concours anymore. Freshmen as Yuuta and the other know nothing why their seniors said something as pessimistic as that. Until one day, they found the cause as a troublesome matters they cannot interfere.