Asuka Tanaka, a third-year student at Kitauji High School during the series' main timeline, holds the position of vice president for the school's concert band club. She plays the euphonium, leading the ensemble's bass section, and also serves as the drum major for marching band performances.

Outwardly, Asuka projects a playful, mischievous, and cheerful personality, frequently teasing others while speaking in a distinctive Kansai dialect. This lively demeanor is later revealed as a deliberate facade constructed to conceal her deeper, more complex emotions and vulnerabilities from her peers and club members.

After graduating from Kitauji High School, Asuka maintains ties to the concert band. She returns as an alumnus to observe the band's performance at the Kansai competition during Kumiko Oumae's second year, joining fellow former members Kaori Nakaseko and Haruka Ogasawara, demonstrating her continued investment in the band's progress and achievements.