Mio Kanzaki is a second-year student at Hakuto High School and a member of its koto club. He has dark hair that is often left unkempt and brown eyes. His demeanor is notably monotone, speaking and reacting with a flat, unchanging expression that makes him appear detached or uninterested at first glance. Despite this reserved exterior, Mio is deeply dedicated to the koto and takes his responsibilities within the club seriously. He possesses a rare condition called chromesthesia, which allows him to visually perceive sounds as colors and shapes. This unique ability gives him an exceptional sense of rhythm and a distinctive approach to music that sets him apart from other players. Mio has known Uta Suzumori since childhood and began playing the koto alongside her when they were six years old, forming a close bond that continues into high school. While he tends to keep to himself, he is reliable and willing to help his clubmates with both musical practice and personal matters when needed. Over the course of the story, Mio's quiet dedication and his willingness to support the group contribute to the club's growth and collective sound, and he gradually becomes more comfortable expressing himself through his playing.