Sound! Euphonium: The Movie – Our Promise: A Brand New Day is a 2019 Japanese animated film based on the novel series Sound! Euphonium by Ayano Takeda and a sequel to the two seasons of the anime television series adaptation. Produced by Kyoto Animation and distributed by Shochiku, the film is directed by Tatsuya Ishihara from a script written by Jukki Hanada. The film follows Kumiko Ōmae in her second year at Kitauji High School mentoring new first-year students who have joined the school's concert band.

The film was one of the two new anime projects announced by the studio in June 2017, with Ishihara being confirmed as its director. It received its official title in June 2018, with Tomoyo Kurosawa confirming her return to voice Kumiko and new characters being unveiled. Additional staff and cast were revealed in September and December 2018.

Sound! Euphonium: The Movie – Our Promise: A Brand New Day had a screening in Yūrakuchō, Tokyo on April 5, 2019, and was released in Japan on April 19. The film grossed over $3 million worldwide. It is followed by an anime television series featuring Kumiko as a third-year student, which premiered in Japan on April 7, 2024.