Mr. Priest, an unnamed young exorcist the Church raised to follow scripture to the letter, exorcised Asmodeus, the Demon Lord of Lust, at twelve and had repelled three of the Seven Lords of Sin by sixteen. When Satan summons Imuri Atsuki, the artist behind the exhibition The Gallery of Evil, to Gehenna, Mr. Priest is assigned to guard her. What the Church does not know is that Imuri is a succubus, and her instructions are to make the world's strongest exorcist fall in love.