Bab 1145: The Fall of the Seresian

The other two worlds are created by the Demon Emperor where he put all of the captives that the Seresian world had conquered. 

From what Azief understood, the Demon Emperor and his army once went into an expedition outside of the Seresian world, conquering low level worlds.

The Seresian world needed resources as the world itself is dying. 

The living being that they captured from other worlds is not strong enough to become their threat but good enough that they could supply certain workforce to their world.

Because the Seresian world population had a drop in fertility, the population of the Seresian true demon is decreasing year by year.

As for the Seresian demonic soldiers most of them are born in the Rebirth Hub. 

As such, they grow fast but they also die fast and with their low level intelligence, they are not suitable to take the torch of the legacy of the Seresian demon

Everything has a price.