Tazuki Kamiya possesses blue hair with a fringe covering his right eye and distinctive golden eyes. He stands taller than his childhood friend Sora Kashiwagi, maintaining a lean build.

A childhood encounter defines a core aspect of his being: discovering an injured baby dragon pursued by a collector, he sheltered it within a dilapidated building. Attempting an escape through a window, unaware the creature couldn't fly, resulted in severe injuries. This event left permanent scarring on his arm and instilled lasting trauma regarding responsibility for supernatural beings. It forged his initial reluctance to form attachments, leading him to dissuade Sora from caring for injured animals and influencing his early rejection of Conny.

Outwardly cool and organized, Tazuki possesses heightened observational skills, including exceptional eyesight enabling him to perceive distant minute details and supernatural entities invisible to others, like Mii's Shikigami. Academically proficient, he assists Sora with studies yet struggles significantly with artistic endeavors such as doll-making and decorative sushi. He finds emotional expression challenging and becomes defensive around strangers, yet exhibits fierce loyalty and protectiveness toward those close to him, displaying frightening intensity when they are threatened. A persistent, occasional sadistic curiosity manifests as his desire to uncover what lies beneath Mii's bandages, though Mii's overwhelming cuteness ultimately deters him from acting.

His closest bond is with Sora Kashiwagi, a relationship originating in preschool so profound that the Kashiwagis consider Tazuki virtually family. He maintains vigilance over Sora due to Sora's tendency toward isolation, their connection deepened by mutual encounters with the supernatural. Tazuki withholds information about "Collectors" from Sora, honoring a promise to Sora's aunt, Mokuren.

His emotional development centers on caring for Conny, an oni child he initially abandoned due to his trauma. After finding the injured Conny following him home, Tazuki named him but continued pushing him away. Conny's persistent efforts and the discovery of shared scars mirroring Tazuki's own childhood injury gradually eroded his resistance. When Conny temporarily ran away following a harsh rejection, Tazuki confronted his fears, acknowledged his attachment, and fully accepted Conny into his family. Their relationship involves frequent bickering, with Conny responding physically to Tazuki's teasing remarks, yet both express care through this unique dynamic.

He also maintains other relationships: a cautious fascination with Mii-kun despite the bandage-related curiosity; initial hostility toward Daichi Tachiaki after threats against Sora and Motegi, later transitioning to friendship upon understanding Daichi's circumstances and receiving an apology; and a protective role toward his younger sister, Tsukiyo Kamiya.