Assistant to the Demon Lord. S-Rank. An elderly demon who summoned Guest. He will follow whatever decision Guest makes as the Demon Lord and will never betray them. He treats Guest in a friendly manner. He wants Guest to become the Demon Lord. He served as the assistant to the previous Demon Lord, but after the previous lord died of illness and there were no other candidates, he decided to summon Guest. Magic: Shadow Magic. He can dive into shadows and move objects in and out of them. Living beings other than himself cannot enter the shadows. By entering a living being's shadow, he can manipulate their movements.

Maid to the Demon Lord. A-Rank. Initially, she does not recognize Guest as the Demon Lord. Indira is her mentor, and she trusts him deeply. She rarely causes actual harm to Guest. Tsundere. She has a strong-willed personality and will not yield even to those stronger than herself. Magic: Raging Fire Magic. Magic that releases and manipulates flames from her body. The temperature of the flames can be adjusted, reaching up to 10 million degrees.

Maid to the Demon Lord. A-Rank. She has a timid personality and is always with Aruna. Initially, she is terrified of Guest and finds it hard to approach. She has a kind heart, and Aruna always protects her. She is Indira's disciple and respects him. She is a coward and rarely uses her magic. Magic: Taming Magic. Magic that summons giant, terrifying-looking magical beasts. Normally, it should allow the user to subjugate these beasts, but Meryl either faints or collapses in fear the moment she sees them, making subjugation impossible.

King of the Human Kingdom. SS-Rank. Publicly, he has a kind and cheerful personality and is seen as a merciful man. His true face is that of a bigot; he discriminates against anyone B-class or lower and demons, viewing no one except A-class knights and nobles as human. He never shows his true nature to the citizens of his country. He gives speeches to his soldiers to boost morale, but every word is a lie, and he views the soldiers as nothing more than disposable pawns. He rarely leaves the royal capital where his castle is located. Magic: Light Magic. He can manipulate light at will. He can fire massive amounts of light lasers at once, or bend the lasers to track targets. By riding on a disc of light, he can fly or move the disc to travel at the speed of light.

A reincarnated person like Guest. SS-Rank. She was reincarnated at the exact same time as Guest. Before reincarnating, she was the head of the school disciplinary committee and is extremely strict about rules. Her sense of justice is hundreds of times stronger than the average person's. She has been told by Hitler that Guest is the worst kind of Demon Lord. A few days after reincarnating, she will lead an attack on the Demon Lord's castle. Magic: Holy Sword Magic. Summons a Holy Sword to fight. The Holy Sword can cut through anything. The protection of the Holy Sword is active.