I'm Quitting Heroing

People look to the hero Leo Demonheart to defend them when Demon Queen Echidna starts her invasion of the human realm. Leo easily defeats Echidna's army thanks to his invincible strength, rescuing the world. But instead of appreciation or admiration, Leo's fellow humans treat him with derision and contempt because they are afraid of his imposing power and think it could ultimately lead to humanity's extinction. After being exiled from the realm he once called home, Leo wanders aimlessly around the countryside until he learns of Echidna's attempts to reassemble her army one day. He goes back to the demon queen's castle and offers Echidna his assistance in the hopes that demonkind will welcome him as an ally. Naturally, Echidna rejects him right away. Even so, there is still some hope because Leo is able to persuade the four generals of Echidna to permit him to work in secret under their watch. Leo assumes the persona of a masked dark knight named Onyx and addresses each issue that the demon army presents, eventually enhancing life in the area of the castle. Leo, however, has one thing in mind above all else: to find out why Echidna launched the battle in the first place.