Kumiko Oumae, who had previously given up on music due to an incident at the middle school regional concert band competition, entered high school with the hope of starting fresh. To her surprise, she found herself surrounded by individuals interested in the high school brass band. With the help of her new and old friends, including novice tubist Hazuki Katou, veteran contrabassist Sapphire Kawashima, and band vice president Asuka Tanaka, Kumiko discovered the motivation to make music once again. However, despite their desire to compete nationally, the band faced numerous challenges due to chaos within its ranks. Noboru Taki, the new band advisor, needed to take action in order for them to successfully participate in the local festival.