Early story:
The gates of Hell opened at the end of the Yuan Dynasty. The dead rose again, transformed into bloodthirsty undead.
To fight the undead, the Yuan Dynasty secretly established the Reaper Church.
When the Yuan Dynasty fell and the Ming Dynasty was founded, the Ming declared the Reaper Church an enemy.
And so the Ming began hunting down the Reaper Church.
The Reaper Church fought both the Ming and supernatural creatures.
As time passed, an even greater crisis emerged. Demons from another world were plotting to destroy humanity.
Worldbuilding:
The Creator made countless parallel universes. But the thing He regretted most was creating humanity.
Humanity's wickedness enraged the Creator. He decided to wipe out humanity in every parallel universe.
After careful consideration, the Creator decided to entrust the task to the demons.
Humans of the Stone Age, the Iron Age, and the Industrial Age will all face demonic invasions.
