Following the revelations of the archangel Gabriel, Ente Isla hero Emilia Justina—who lives on Earth under the alias Emi Yusa—starts doubting the validity of her mission to slay the Demon Lord Satan, now reduced to a modest employee of MgRonald's as Sadao Maou. At the same time, Sadao's high school-aged coworker Chiho Sasaki pursues a new dream with hopes to protect not only herself but also her friends. Secretly training with Emi and Suzuno Kamazuki to develop telepathic powers, Chiho's training is cut short when a group of demons abducts her.

As angel and demon attacks threaten the fragile peace between the two worlds, Sadao and Emi need to put their troubled past behind them if they want to have a chance to find their new purpose in life.