Leviathan

Leviathan is a demon and he is the third-oldest of seven brothers and the Avatar of Envy. Leviathan is known for being a hardcore otaku, full-time shut-in, and his only friend is his goldfish named Henry. Leviathan has a huge seven headed sea monster named Lotan, he summons Lotan when he's in danger and needs help, but when summoning Lotan, huge amount of water is summoned as well causing a flood.