Totsuka Maria was praying in a chapel at Seiseki Girls' Academy when a black cross comes falling from the sky. On that cross, was a fallen angel, bearing the sin of pride, Lucifer. Maria attempt to tend to the angel, but the floor falls out and she disappears. Lucifer finds herself in the depths of hell, and runs into the Demon Lord of Envy, Leviathan.
I'm the demon lord
 that controls water, Leviathan.
Ich bin der dämonische Herrscher
des Wassers, Leviathan.
El demonio que controla
el agua, Leviatán.
El demonio que controla
el agua, Leviatán.
Le seigneur démon de l’eau,
Léviathan.
Sono la Potenza Demoniaca
che controlla le acque, Leviathan.
Sou Leviathan, o demônio 
que controla a água.
Я демон, управляющий водой — Левиафан.