The Leviathan. Also known as Behemoth, colossus or titan among other things.
It is said it lived in the deepest and most terrifying parts of the oceans. With its massive body and monstrous, nothing was save within the boundless oceans. The beast harboured the oceans as its territory.
But in all ages. No one has ever seen it. Those who spoke of it, only refer to it as a myth. Or whimpers in the air. Maybe that was because no preys have ever escaped its grasp.
But there what people called its traces in existence. The children of Leviathan. Giant serpents that roamed the open seas like their own.
Some time after Ryuga's apparent death, Ryukka reincarnated. And some time during the run of the life, she sensed it.
The servant attacked attacked ships filled with troops. On which she was on one of them. The beast took on all elite fighters, and the overwhelming might of troops. Even with their might, they were hopeless.