As she set foot in Kitauji High School, Kumiko Oumae hoped to put her past behind her. However, her new friends Sapphire Kawashima and Hazuki Katou convinced her to join the school's band club, where she found herself playing the euphonium once again. Unfortunately, the band was in disarray and not ready for the upcoming local festival, let alone national competitions. The new advisor, Noboru Taki, gave the group two options: keep things casual or push themselves to compete on a national level. Kumiko was hesitant to try again after past failures in middle school. To complicate matters, she discovered that Reina Kousaka, with whom she had a rocky history, had also joined the band. Under Noboru's strict training, Kumiko and her fellow musicians had to work through their problems and synchronize their playing. They went through struggles to make it to nationals, but they realized that they needed to work hard if they wanted to achieve their goals.