I’m Quitting Heroing, Vol. 1 English Version Manga

For the Hero, Leo Demonhart, saving the world isn’t all it’s cracked up to be. After he vanquishes Demon Queen Echidna, the “grateful” people would rather give him the stink eye than show any respect. Now he’s come to Echidna’s castle with résumé in hand, but his old foe isn’t exactly fond of the guy who trounced her forces. It’s up to Leo to use every trick he knows and get in her good (evil?) graces—a cushy gig as a minion of darkness is on the line!