I have known gods to die before, but the rebirth process never seems to cause this kind of turmoil, as far as I knew. I have heard that one of the gods has returned already, which is confusing to me. I will have to ponder it more at a later time.

The way it was explained to me was that the followers of those gods who were killed were left in such a state that they became prey for ayakashi with their prayers going unanswered, thus why we believe that taking care of the ayakashi or by answering their prayers, we can quell what harm has been done until the gods are reborn.