Akamatsu:from a God to a Demon

"what happened to this world"a boy said"run away akamatsu"someone else said as a monster ate him"no......not him why"monsters are all over Tokyo this is a very hard world .if a monster dies a rebirth of another monster will arrive at the same place,but why is this happening is there someone that wished for this to happen.will this mysterious boy named akamatsu find out