Kanji Kageyama upholds his family’s medical legacy by managing their clinic after completing his education. His decades-long friendship with Yashiro began in high school, where he routinely treated Yashiro’s injuries from unspecified incidents. Though aware of Yashiro’s volatile behavior and traumatic history, Kageyama steadfastly supports him, navigating his friend’s self-destructive patterns without severing ties.

Professionally, Kageyama balances daytime medical practice with clandestine nighttime treatments for Yakuza affiliates under Yashiro’s command, intertwining his ethical obligations with underworld loyalties. His clinical fascination with scars and burns extends beyond his work, influencing personal desires.

Yashiro once harbored unreciprocated romantic feelings for Kageyama, who later formed a relationship with Eishin Kuga—a scarred former delinquent whose traumatic childhood abuse shaped his demeanor. Their dynamic, detailed in the prequel *Don’t Stay Gold*, explores Kuga’s past and the bond forged through shared vulnerabilities.

Kageyama’s quiet, conflict-averse nature and emotional reserve counterbalance Yashiro’s unpredictability, positioning him as both healer and anchor within their fraught dynamic. Black-haired and bespectacled, his composed professional facade contrasts with a cigarette habit and morally ambiguous nighttime activities. While supplementary materials in *Distant Flame* allude to his peripheral ties to broader events, his primary narrative remains rooted in navigating duality: medicine and vice, detachment and loyalty, stability and complicity.