Mio Kanzaki has dark, often unkempt hair and brown eyes, speaking in a notably monotone voice marked by unchanging pitch and absent intonation. His musical journey began at age six with koto lessons under the instruction of his cousin Uta Suzumori's mother, learning alongside Uta and establishing his foundational bond with music. He experiences chromesthesia, a neurological condition causing him to perceive sounds as colors or visual patterns without external influence, fundamentally shaping his relationship with music. Socially, he exhibits distinct behaviors such as appearing unexpectedly behind others—particularly Chika Kudo—sometimes resting his chin on Chika's shoulder. This stems from his focused interest in individuals who capture his attention, driving him to actively pursue friendships despite his reserved nature. Within the koto club, he maintains a close association with Taishin Yamamoto. Their interactions frequently involve him lying on the floor while listening to surrounding sounds, accompanied by Yamamoto. Personally, he displays a specific preference for Oreos and expresses confusion toward foods lacking crisp textures. Daydreaming occupies most of his leisure time, as he finds structured recreational activities unusual. He also reports difficulty perceiving internal changes within himself. His given name, Mio, translates to "water route" or "shipping channel," while his surname Kanzaki combines "god" or "deity" with "cape" or "peninsula."