He is so kind that he is often a pushover. He is a boy with a plain appearance, featuring spiky blue hair and blue eyes lighter than his hair color. A large cowlick on his head is his trademark. He is human, a secret known only to Sullivan and Opera, and possesses max-level evasion skills.

He is devoted to Iruma to the point where his loyalty borders on religious faith. He speaks politely to Iruma but is fundamentally kind. Unlike most demons who rely on bloodline abilities, he primarily uses chantless fire magic he mastered himself. He is the only son of Asmodeus Amaryllis. A sharp-looking handsome man with light pink hair tied in a loose ponytail and reddish-purple eyes.

She possesses magic that allows her to pull anything she has seen before out of her pockets. Her personality is so eccentric and airheaded that one might suspect ADHD. She is a cheerful girl with waist-length lime-green hair and green eyes. She features a hime cut, sharp shark-like teeth, and is ambidextrous. She usually goes around hugging Iruma, and eventually, Iruma accepts this behavior as a matter of course.

Cerberion: A sentient magical power passed down through the Naberius family. While he is generally serious, he can be quite high-strung when his composure breaks. He is the lead teacher at Babyls and the homeroom teacher of the Misfit Class.

The chair-demon of the demon school Babyls and Iruma's adoptive grandfather. He dotes on his grandson and helps Iruma adjust to school life.

Sullivan's butler and a 'Security Devil' who handles everything from household chores to external affairs. Though they maintain a poker face and speak little, leading others to think they are cold-blooded, they are actually quite emotional beneath the surface.

The teacher in charge of Netherworld History and the head of the faculty. He is always smiling and is popular among students because he makes his classes fun.

He creates weapons made of the same material he bites with his teeth. Because of this, Sabro wears necklaces made of copper, iron, and gold to activate his ability. While he has a headstrong personality, he strives to possess the character of a Demon King and shows surprisingly sensible traits.

He loves gambling and gaming. Controller (Sense Robbery): He can steal one or more senses from others, paralyzing the target's stolen sense while he experiences it himself. The range of effect depends on his mana and concentration. He shows a side that gets things done when necessary and deeply values his friends.