Motomu Tsukinaga is a first-year student at Kitauji High School, one year below Kumiko Oumae, and a double bassist in the school’s concert band. He is introduced in Kumiko’s second year and continues to appear in the third season. He has an androgynous appearance and is often mistaken for a girl, a fact that irritates him. He is generally quiet, aloof, and easily displeased, with a notoriously prickly personality that makes him stand out even among the seasoned members of the low brass section. He strongly dislikes being called by his surname, Tsukinaga, because it constantly reminds others of his famous grandfather, a renowned brass band instructor. This sensitivity to being seen only as an extension of his family is a key aspect of his character. He came from the attached junior high of Ryusei Academy, a private boys’ school, but chose to attend Kitauji to escape the pressure of being judged solely as the grandson of a celebrated teacher. He also chose Kitauji because he felt a connection with the band’s conductor, Noboru Taki, whose own father was a famous musician and who understood what it was like to be defined by a relative’s reputation. Motomu’s older sister, Michiru, who played double bass, died three years before the story begins. He took up the same instrument to honor her memory. Initially, he showed little enthusiasm for the double bass, claiming that anyone could play it, but after hearing his senpai Sapphire Kawashima (Midori) perform, he was deeply impressed and asked to become her disciple. Under her patient guidance, he became sincerely devoted to the instrument and to her as a mentor. His relationship with Midori is central to his growth; he respects her playing and her personality immensely, and he often acts like a loyal, obedient follower around her. He has admitted that Midori reminds him of his late sister, which adds a layer of emotional depth to their bond. Over the course of the story, Motomu softens slightly, learning to trust his new environment and to express his commitment to the band. By the third season, he is fully integrated into the ensemble, working hard to improve his technique and contribute to the group’s goal of winning a national gold medal. His notable ability is his growing proficiency on the double bass, which evolves from disinterest to focused effort thanks to Midori’s teaching and his own inner drive to connect with his sister’s legacy.