"In the Sasazuka neighborhood of the Shibuya district of Tokyo, newly minted part-time burger-flipper and former Devil King Satan (now known as Sadao Maou) clashes with Lucifer, a fallen angel who used to serve him! But how will the onetime king deal with his rival now that his magic power's run dry? Now that the devil is one of us, he's going to have to get creative!" -- Unedited summary from the book.