If you loved Sound! Euphonium the Movie – Our Promise: A Brand New Day, try Love, Chunibyo & Other Delusions! Rikka Version
A bridge between a film you've already seen and one most people haven't. Here's what they share, and what the second one does that the first one doesn't.
You already loved

Sound! Euphonium the Movie – Our Promise: A Brand New Day
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Love, Chunibyo & Other Delusions! Rikka Version
What they share
Both films are directed by Tatsuya Ishihara, and they both carry the bittersweet, tender mood tags, and they sit in Animation / Drama territory. If that's the register that drew you to Sound! Euphonium the Movie – Our Promise: A Brand New Day, the second film will land in a comparable space — through a different lens.
bittersweettender
What Love, Chunibyo & Other Delusions! Rikka Version is
Apparently romance can be found in delusions. Rikka's perspective retells the first season with new elements. It somehow ties everything together.