Black-level monster

"Black-level monster" was a general name for monsters that were as intelligent as men and able to practice like them.

It was widely known that monsters had strong bodies. If they could practice like human beings, it would be difficult to say who would dominate the earth.

It was just that black-level monsters were very rare, especially natural born ones. They were almost extinct 500 years ago, but some monsters became black-level monsters due to an unknown variation when the fierce prehistoric beast blood in their bodies was awoken.