This is a world filled with monsters.
After the battle between humans and monsters, the winner took control of the world, while the loser left the stage of history forever.
After the Demon King came to power, he was afraid of the powerful power of the demon clan and implemented a comprehensive ban on demons. Common people were prohibited from learning demon arts. Adult demon clansmen who had already learned them were not allowed to continue to practice, let alone use them.
There is a monster detector in the center of every town, which can detect monsters within a thousand miles radius.
Any demon clan that uses demon power secretly will be killed without mercy once discovered.
Later, the Demon King issued a demon-slaying order and used unknown means to kill all the great demons who were over the age of eight. In order to save their lives, the demons who have not reached the eighth level have to swear allegiance and turn all their demon power into inner elixirs and give them to the demon emperor.
As time goes by, the common people of the demon clan no longer recognize the demon magic...
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Purpose: Young masters and apprentices overthrow the tyranny of the Demon Emperor