Devil is a part-timer! (manga)

"It's tough being evil when you have to pay the rent! This comical tale of a demon-lord-turned-fry-slinger follows the daily travails of (former) Devil King Sadao Maou and his general Shiro Ashiya as they navigate the complexities of life in modern-day Tokyo. Having suffered utter defeat at the hands of a plucky hero, they've been banished to earth and stripped of magical power. And if that wasn't enough, that pesky hero is still hell bent on finishing...

"Speak of the devil, and he'll fry you a burger! Sadao Maou, (aka Satan, the Devil King) has been relegated to flipping burgers at a MgRonald in suburban Tokyo. His greatest challenge so far, though, comes when a Sentucky Fried Chicken opens up across the street. Maou once led the forces of darkness, but can he triumph over the forces of chicken? And the new girl next door seems awfully polite and proper, almost as if she were hiding something..."--Back...

"Being soundly thrashed by the hero Emilia, the Devil King and his general beat a hasty retreat to a parallel universe...only to land smack in the middle of bustling, modern-day Tokyo! Lacking the magic necessary to return home, the two are forced to assume human identities and live average human lives until they can find a better solution. And to make ends meet, Satan finds gainful employment at a nearby fast food joint! With his devilish mind set...