Since his childhood, Touma Godou has been unable to use magic, and as a result, he was despised and treated as incompetent by his own father. As a result, he was sacrificed on the island of Kyokuma. Where wild demons roam. But there he meets a demigod who helps him master the art of combat until he becomes invincible. One day a girl called Liz appears on the dangerous island, Touma vows to protect her and they both escape from the island while hiding their secret of being the most powerful man in the world in order not to affect their own survival in the world and the human race.