Nagakabouros

To Illaoi, Aurelion Sol says he's, "seen the main act."

He may exaggerate his strength relative to the game itself, but none of his lines are outright lies (except his slight contradiction between saying all things appreciate in value and that some things are better with age).

So I believe he actually has seen Nagakabouros. That it's no more a "God" to be worshiped than he is. Albeit his lore does say he's been worshiped as a god. But Nagakabouros must be another cosmic entity with power on par with Sol or Bard.

I'd like to see something official for what Nagakabouros actually is, and what Illaoi's totem actually is.