HaruChika: Haruta to Chika wa Seishun suru

Manga adaptation of the HaruChika novel series by Sei Hatsuno.
The original novels revolve around two high school students named Haruta and Chika, who are members of a wind instrument club that is on the verge of being shut down. The two are childhood friends, and they spend their days practicing hard while also trying to recruit new members. When a certain incident happens within their school, they work together to solve it.
(Source: Anime News Network)