Demons.
They've always been depicted in oral story-telling, literature, and known in every culture as horrible, ugly beasts that devour humans, annihilate civilizations, and ruin lives.
But now they're just little pests to humans.
Ever since the countries came up with their own Demon Killing Machines, humans have not been able to see, nor do they care, about the evil beasts that tortured their ancestors long ago.
Until one country awakes a macabre beast.
One that destroyed their land long ago.