When Demon King Satan was facing his demise at the hands of Hero Emilia, he had no choice but to quickly flee to another world with his Demon General, Alsiel. However, upon their arrival, the twosome is taken aback with the realization they have lost almost all of their magic - and moreover, were transformed into ordinary humans and are stranded in an otherworldly place called Japan! To survive, the Demon King must now work a part-time job at a fast-food joint and attempt to adapt to modern society the best the pair can as Japanese citizens, all while scheming to rule over the country in the process. But with Hero Emilia and others on Satan’s tail to slay him for good, will Japan ever become his new domain?