After leading a rebellion against the will of the Lord, Lucifer, a former Archangel and head of the Seven Heavenly Virtues, is banished from Heaven. She hurtles towards Earth, crashing through the ceiling of a church in a high school. Although spotted by Maria Totsuka, a gentle student, Lucifer quickly plummets into the depths of Hell. Stranded in the underworld, Lucifer joins forces with a fervent demon, Leviathan, in a plot to overthrow the Seven Sins, malicious leaders of Hell obedient to Belial. However, despite their combined strength, the Seven Sins prove to be an impenetrable force. To counter her divine powers, they seal her in a cursed garment known as the Garb of Punishment, turning her into a Demon Lord. Full of bitterness and accompanied by Leviathan, Lucifer returns to Earth, where she subjugates Maria, forcing the girl to be her eternal servant. Together, they launch an offensive against the Seven Sins, driven to break the curse of her imprisonment and claim her freedom.