Claymore is set in a fictional world with medieval technology. Politically, it appears to consist of a large number of scattered, apparently independent, towns. In this world, humans coexist with creatures called Yoma, sentient monsters that feed on human organs. The Yoma, being shapeshifters, are capable of taking on a human form and living in disguise amongst humans. By consuming a human's brain, Yoma can also absorb their memories, allowing them to disguise themselves as specific people without alerting even their close friends or family. A nameless and highly secretive organization has created an order of superhuman warriors to protect humans from the Yoma. These warriors have come to be popularly known as Claymores, after the immense claymores they wield. Villages being attacked by Yoma hire Claymores to kill the Yoma for a large fee.