|Birthday||January 15 (Capricorn)|
|Role||Tenor Saxophone player|
|Occupation||Student (third year)|
|School||Kitauji High School|
Aoi Saitou (斎藤 葵 Saitō Aoi ) is a character in the Hibike! Euphonium series. She is a third year who quit the Kitauji brass band, having played the tenor saxophone since middle school.
Aoi is a teenage girl of below average height and build, who wears the standard Kitauji High School uniform for female third-year students. Her dark brownish green hair is braided, her bangs are clipped back by two light blue barrettes, and she has light green eyes.
Aoi is a very friendly and disciplined girl, who is rarely seen being mad or upset, in which she is calm in most situations and takes everything nicely. She is also mature, reliable and understanding, seen as she gives Kumiko advice. This is why she is also seen as a responsible girl.
Aoi was first introduced in Nice to Meet You, Euphonium, where she appears when Kumiko and Shuuichi were talking, and thus meeting them after a long time.
Later, in Crybaby Saxophone, she announces that she will be quitting the band, since she is currently struggling with balancing academics and participation in the concert band, in order to focus her attention on her academics. She was also partially motivated to quit because of her disappointment in her inability to prevent the schism of the previous year from transpiring.
Kumiko and Aoi are childhood friends that lost contact but are later reunited when Kumiko joined the concert band in Kitauji High. They are on good terms, often chatting and hanging out after school despite Aoi being two years older than her. Kumiko can openly talk to Aoi when she needs help, since she knows Aoi is a very kind person and will listen. After Aoi quit the band, they, once again, lost their contact; since the two are rarely seen to interact anymore and Kumiko was sad to find out that Aoi never really regretted leaving the band.
Shuuichi is also Aoi's childhood friend. They haven't interacted much, but they seemed to have a close relationship is the past, and they later developed a quite friendly relationship after reuniting in high school.
- Aoi resembles Youko Sasaki, a side character from K-ON!, which is also animated by Kyoto Animation.
- She originally wanted to go to Horiyama High School.
- On her bag in the novel, she has a little "deformed yellow rabbit" charm keychain.