Kazusa Ōtori is a student at Himesaka Girls' Academy and a member of the school’s koto club. She possesses long, light wavy hair and brown eyes, and is usually dressed in her school uniform. Her surname, Ōtori, translates to "phoenix" or "firebird." As the daughter and heiress of the head family of the Kao School of koto, Kazusa has admired Satowa Hozuki’s koto performances since childhood. She deeply respects Satowa’s musical ability and actively encourages her to attend Himesaka Girls' Academy so they can perform together. Her determination to play alongside Satowa verges on obsession, fueled by her belief that the members of the Tokise High School Koto Club cannot match Satowa’s skill. Kazusa is close friends with Fumi Hanamura, and the two are often seen together, frequently going shopping in their leisure time. She enjoys cute-looking confections and has a distinct aversion to grotesque objects. On holidays, she spends her time listening to Satowa’s performances, practicing koto, or shopping with Fumi. Kazusa carries a fierce demeanor, which has so far discouraged any romantic interest from boys.