Satan, the Devil King of Ente Isla, is on the verge of conquering that world when the hero Emilia drives him back and forces him through a gate that dumps him in modern Tokyo. Stripped of nearly all his magic, he takes the human name Sadao Maou and lands a part-time job at a MgRonald's counter to make rent, while his general Alciel keeps house. His plan to fund a way home gets complicated when Emi Yusa, who is Emilia and is stranded on Earth too, tracks him down.