Sound! Euphonium describes the day-to-day life of members of Kitauji High School's music club as they compete in national competitions. The club has never succeeded in propelling its students beyond the Kansai regional competitions, but this year things begin to change with the arrival of a new advisor and his rigorous methods. However, each student faces a personal dilemma; between the one who needs to focus on her studies, the one who struggles to excel in her solos, or the one who lacks confidence in her own skills... What future awaits them?