Manga Maou Gun Saikyou No Majutsushi Wa Ningen Datta

He is an incredibly powerful monster who, with his magic, is capable of single-handedly destroying an entire fort. He possesses incredible powerful power, because of which others fear him. At the same time, he hides a secret from other demons, since in fact he is a human being. But he uses modern technology to hide this fact, and to be one of the leaders of the mighty army of demons.