Mayu is a fairly short teenage girl with long, straight light brown hair and bright turquoise eyes. She initially wears her Seira High School uniform before switching to the Kitauji uniform.

Mayu is friendly and caring but keeps a respectful distance from others. She is calm, quiet, and prefers to be transparent, avoiding being the center of attention. Despite her reserved nature, she is deeply passionate about music and never plays halfheartedly. Midori once compared her to a jellyfish: pretty from afar, but with hidden stings if approached too closely.

Mayu arrives at Kitauji High School as a third-year transfer student. She is assigned to Kumiko’s class and quickly befriends her, Hazuki Katou, Midori, and Tsubame Kamaya. She worries about being a burden in the band, as she plays the same instrument as Kumiko, and repeatedly asks whether she should forfeit solos.

Over time, she forms a close bond with Tsubame and navigates band dramas with a neutral stance, believing the club should be enjoyed by everyone. At practice camp, she earns the euphonium-trompet solo after a second audition, which worries her about Kumiko’s feelings, but both Tsubame and Kumiko reassure her. Right before nationals, she and Kumiko discuss their feelings openly, and Mayu emphasizes that she values playing with others above winning the solo. Mayu ultimately wins the solo by one vote, and her heartfelt performance with the band leads to an emotional gold award, leaving her relieved and happy alongside her friends.