As the band club's president at Kitauji High School, Kumiko Oumae grapples with excitement and trepidation. She ponders the arrival of new members, her ability to lead the band effectively, and the elusive dream of clinching a gold medal at the national competition. Balancing her duties as the club's head and a performer, Kumiko faces a formidable challenge in the form of transfer student Mayu Kuroe. Armed with an identical instrument, the euphonium, Mayu charms everyone with her exceptional talent and amiable nature, casting a daunting shadow over Kumiko. As the specter of 'graduation' looms over these dedicated youths immersed in the world of brass bands, tensions and aspirations run high.