The arrival of unknown existence destroyed human civilization and order.
There are countless monsters to kill.
Humanity was forced to retreat.
A miracle occurs.
Human beings have discovered that there are special worlds underground, worlds like caves.
The crypts are extremely numerous, huge in size, and connected in series with each other. The total area even exceeds the total surface of the earth.
There are many kinds of creatures inside the cave and there are sufficient resources.
Humanity found countless resources in it, finally withstood the monster attack, and rebuilt civilization and order underground.
This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.
