Leviathan is one of the princes of hell. He is the ruler of the sea and the king of all sea monsters. He is renowned for having a charming appearance, almost on par with Lucifer. But behind its appearance, Leviathan really hates humans and angels alike. For him, the two races were just a nuisance and a destroyer. When you accidentally summon it with a magic circle, Leviathan is forced to enter into a contract with you because he can't return to hell until you break the contract.