Ike is known as "the strongest magician in the demon king's army" and is a single-handedly conquering fortresses.
The way he mowed down the 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."

Aiming for a coexistence between demons and humans while the leader of demon's army is hiding the fact that he is actually a human!?

[Source: Happinet]