Lucifer, an Archangel and former head of the Seven Heavenly Virtues, is banished from Heaven after revolting against the Lord's will. While plummeting from the skies, she is halted halfway between Heaven and Hell after crashing through the roof of a high school church. Though she is witnessed by Maria Totsuka, a soft-spoken student at the academy, Lucifer swiftly continues her descent into the depths of Hell. Soon after her arrival, Lucifer is found by aspiring Demon Lord and fangirl Leviathan. The two decide to overthrow the Seven Sins, the authorities of Hell under the leadership of Belial. But with their combined powers, the Seven Sins are able to repel Lucifer and contain her divine powers by placing a Garb of Punishment over her body, transforming Lucifer into a Demon Lord.