Spring in the first year of high school. Kumiko, a member of the brass band in junior high school, visits the high school brass band club with classmates Hazuki and Sapphire. There, she comes across Reina, her former classmate from junior high. Hazuki and Sapphire decide to join the club, but Kumiko can’t make up her mind. She recollects her experience with Reina at a competition in junior high school.

Kumiko and her teammates have won the Kyoto regional tournament. From now on, life will be getting a lot more hectic. With the national tournament fast approaching, Kumiko's band is doubling down on practice and discipline, leaving little time for sleep or other recreational activities. The redoubled practice schedule brings Kumiko and Reina closer together, but elsewhere in the band, it seems like drama threatens to tear the group's unity apart. The ghost of the prior year's mass band exodus still haunts many of Kumiko's classmates, and with former band member Nozomi Masumi now asking to return, it seems like the grudges of the past will soon be impossible to ignore.

Kumiko's third year finally begins! With the concert band at Kitauji High School over 90 members, Kumiko is now the president and does her best with her final high school club activities to try to win her long-desired gold at nationals.