the devil is a part timer Manga
From Yen Press: After being soundly thrashed by the hero Emilia, the Devil King and his general beat a hasty retreat to a parallel universe…only to land plop 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 on working his way up the management food chain, what will become of his thirst for conquest?!
Free Online Read Manga the devil is a part timer