Sound! Euphonium follows the story of Kumiko Oumae, a high school student who joins her school’s brass band club. After a disappointing experience in middle school, where her band failed to qualify for a competition, Kumiko is hesitant about her passion for music. However, when she meets her classmates Reina, Hazuki, and Sapphire, she is drawn back into the world of brass band music.

The anime focuses on the challenges faced by the band as they prepare for national competitions. With intense rehearsals, conflicts between members, and individual struggles, the characters grow both musically and personally. Kumiko’s journey is one of self-discovery, finding confidence in her talent, and rekindling her love for music.

At the heart of the story are the relationships between the band members, their personal goals, and the emotional highs and lows of striving for excellence.