The world ended eons ago and it was all caused by the mysterious entity known as "The Black Hand".

The humans who found this entity began to worship it as if it were a god, and because of this, the entire world ended up being destroyed by a great flood, humanity that worshipped the black hand was granted eternal life and immortality, causing them to constantly revive from the dead, but this causes the corruption of humanity, causing their immortal bodies to eventually rot, crust over and decay for eternity, until they became beings called "the rotlings"

but, there was a prophecy that the human born from the angel's egg would end the reign of the black hand and put an end to the eternal life of the Rotlings.