The anime follows Ike, the protagonist raised as a demon who is feared as the strongest magician of the demon army. While hiding his human identity, he aims for coexistence between demons and humans in this rise-to-power dark fantasy.

Ike is known as "the strongest magician in the demon king's army" and has single-handedly conquered fortresses. The way he mowed down enemies with his immense magic is truly a "monster" that makes him feared by both allies and foes alike. However, he had a secret that he could not tell other demons: " I'm actually human." He aims for coexistence between demons and humans while the leader of the demon's army hides that he is actually a human.—Anime News Network

Ike is a powerful magician and the leader of the Immortal Brigade, part of the Seventh Corps of the Demon Lord's Army. He single-handedly conquers fortresses and pushes back the armies of humanity. Neither Dairokuten, the Demon Lord, nor Ike's loyal soldiers know his darkest secret-he is a human in hiding. But can he keep his secret safe and bring peaceful coexistence to demons and humans??—Crunchyroll