The slave system. It is a system mainly established for humans to persecute beastman. Long ago, when the beastman had no own country, no status or authority, many of them were turned into slaves by humans as domestic animals. Nowadays the slave system was abolished, but is still used behind the scenes in form of slave markets.
Magic Lock Crest[]
Kidnapped at a young age, slaves get a crest called Magic Lock Crest engraved onto their bodies. The mark prevented them from running away or rebelling by letting the magic power in their bodies react to such attempts, giving them intense pain.
No one but the master can erase it. Though it automatically disappears when the master dies.