After forming a contract with the Demon Queen Erinyes and gaining the most powerful mana of any mage in history, the future is looking bright for Eugene and Sumire, the reincarnator from another world. In order to turn Sumire back into a human and return her to her original world, the pair are aiming for the 500th Level of Babel. With the help of the Holy Swordswoman Sara—who still has feelings for Eugene, her former partner—they make short work of Babel’s numerous floors. But a nasty surprise is waiting for them at the Hundredth Level. The Discipline Beast they must defeat is none other than the Demon Queen Erinyes herself!