Enma Daiō presides as the Great King of Hell and Head Judge, determining the afterlife destinations of the deceased according to their mortal sins. His appearance defies traditional scowling, red-faced depictions, presenting a mild and gentle demeanor characterized by bushy eyebrows and a beard. He typically wears a red yukata and a crown-like hat bearing the kanji for "king" (王). Enma consistently displays a calm and kind personality, approaching subordinates and the deceased with paternal warmth; he rarely exhibits anger or sadness, even when disrespected for his perceived lack of authority.

As the supreme leader of the Japanese Buddhist hell, Enma oversees a highly organized structure featuring specialized sections like the Eight Great Hells and Eight Cold Hells, each designed for specific sins – such as Tōkatsu Hell for murderers and Shugō Hell for sexual misconduct. Despite his title, he delegates most administrative and disciplinary duties to his chief deputy, Hoozuki, relying on him for political affairs, problem-solving, and even personal ailments like treating slipped discs. This reliance stems from Enma's discomfort with extreme cruelty and his tendency toward leniency, leaving the implementation of harsh judgments to Hoozuki.

Enma is Hoozuki's godfather, having named him after his transformation from a sacrificed human child into a demon. Their relationship is defined by Enma's genuine fondness and trust toward Hoozuki, whom he addresses casually and almost paternally. Hoozuki, however, views him as incompetent and frequently disrespects him, subjecting him to verbal abuse or physical punishments. Enma acknowledges this dynamic, comparing Hoozuki unfavorably to the more subservient assistants of the other Nine Kings of Hell, yet he accepts Hoozuki's behavior without resentment. Their long-standing partnership has fostered mutual understanding of each other's habits, like Enma's lengthy anecdotes about his grandchildren or Hoozuki's aversion to abrupt awakenings.

Rooted in broader Buddhist and Shinto traditions as Yama, a feared judge of the dead, Enma's mythological background includes folk beliefs depicting him punishing liars by tearing out their tongues and historical reverence from students and businessmen for rewarding hard work. This informs his series role, though his characterization emphasizes approachability over sternness.

His role remains consistent as a passive ruler dependent on Hoozuki's efficiency, maintaining hell's order through delegation while embodying a paradox of gentle authority within a realm designed for punishment. No significant character development or backstory beyond his mythological roots and established dynamics is depicted.