The upcoming OVA will cover the Ensemble Concert arc and will have a limited release in theatres across Japan this Summer.
Here is the first teaser trailer for the OVA:
In addition to the OVA, a third season of the TV anime is also in production. The new season will follow Kumiko in her third year in high school, which adapts the sequel novel. The third season is slated for 2024.
Here is the announcement PV:
Hibike! Euphonium: Kitauji Koukou Suisougaku-bu e Youkoso (Sound! Euphonium) is a music novel series written by Ayano Takeda and illustrated by Nikki Asada. The series ran for a total of 12 compiled volumes, published by Takarajimasha from 2017 to 2019. The series was also adapted into a manga in 2014, published under Kono Manga ga Sugoi! Web magazine for a total of 3 volumes. An anime adaptation of the series was produced for the Spring 2015 anime season by Kyoto Animation (Hyouka, Amagi Brilliant Park) with Tatsuya Ishihara (Clannad, Chuunibyou demo Koi ga Shitai!) directing. The anime ran for a total of 13 episodes. An anime film was produced in early 2016 and a second season during the Fall/Autumn 2016 season for 13 episodes. It was soon followed by a spin-off film in 2018, Liz to Aoi Tori
Here is a synopsis of the series from MAL:
Hibike! Euphonium begins when Kumiko Oumae, a girl who was in the brass band club in junior high school, visits her high school’s brass band club as a first year. Kumiko’s classmates Hazuki and Sapphire decide to join the club, but Kumiko sees her old classmate Reina there and hesitates. She remembers an incident she had with Reina at a brass band club contest in junior high school.
The upcoming OVA of Hibike! Euphonium, Hibike! Euphonium: Ensemble Contest, is currently in production for a Summer 2023 theatrical release.