Haruna Hosono (細野 暖奈 Hosono Haruna) is a side character of Sound! Euphonium: The Movie - Our Promise: A Brand New Day film. She is a new first-year at Kitauji High School who joins the band as an alto saxophonist in Kumiko Oumae's second year.
- The name Haruna means "warm/warmth" (暖) (haru) and "apple tree" (奈) (na).
- Haruna's surname Hosono means "fine, dainty, get thin, taper, slender, narrow" (細) (hoso) and "field, wilderness" (野) (no).
- Haruna is the biggest eater of the band who would nonchalantly eat forever and other people think that she can't be stopped.
- She is also good at cooking that she is thinking about making a menu with large portions for her brings her intolerable levels of happiness.
|Kitauji High School Concert Band during Kumiko Oumae's second year|
|Note: Section leaders are shown in bold text|