Mayu Kuroe is a third-year transfer student who joins Kitauji High School from the prestigious Seira Girls High School, a school renowned for its top-level concert band. She plays the euphonium and brings a level of technical skill that rivals that of the band president and fellow euphonium player, Kumiko Oumae. Her background includes frequent moves due to her parents’ work, which has made her accustomed to changing environments but also contributed to a tendency to avoid standing out. In personality, Mayu is polite, gentle, and soft-spoken, often appearing overly apologetic. This demeanor masks an internal discomfort with causing conflict, and she prefers to remain transparent and unobtrusive, even avoiding appearing in her own photographs. She is calm, quiet, and modest, with no strong preferences or desires to assert herself. Her primary motivation is to find her place in a band that already has a strong identity, and she struggles with playing with genuine conviction rather than mere technical perfection. In the story of Sound! Euphonium, The Final Movie Part 1, her arrival creates a complex dynamic within the euphonium section because her ability directly challenges Kumiko’s position, leading to tension over solo placements during the final competition roster selection. Her role is pivotal as the band prepares for nationals, and her interactions are marked by a desire to fit in without displacing established members. Key relationships include a polite but strained dynamic with Kumiko Oumae, a growing closeness with fellow euphonium player Kaho Hariya, and a wary, occasionally hostile interaction with Kanade Hisaishi, who is protective of Kumiko. Over the course of the narrative, Mayu develops from a passive, conflict-avoidant newcomer into a musician who learns to embrace her own voice and play with conviction. Her notable abilities include outstanding euphonium proficiency; she was a first-team member at Seira for two years, placing her among the strongest high school euphonium players in the series’ world.