Just finished the series and it was great!!!

Claymore (クレイモア, Kureimoa^?) is a dark fantasy manga series written and illustrated by Norihiro Yagi produced for Monthly Shonen Jump. As of October 2007, 13 volumes of the original Japanese edition and 11 in English have been released. Each chapter in the manga is referred to as a "scene".

As of June 6 2007, the final issue of Monthly Shonen Jump was released and the magazine cancelled, while the Claymore manga appeared on a monthly basis for a brief period in Weekly Shonen Jump. Claymore continued in the first issue of Jump Square, which was released on November 2, 2007.

An anime series based on the manga began airing in Japan on 2007-04-03.^[1]

The setting of Claymore's story is 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 (妖魔, Yoma^?) sentient monsters that feed on human guts. The Yoma, being shapeshifters, are capable of taking on 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 any of 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.

This organization creates the Claymores by implanting Yoma flesh and blood into humans, thus creating hybrids that are more powerful than the original Yoma, in addition to their weapons training and often greater intelligence. These hybrids use large claymore swords that normal humans lack the strength to wield and are characterized by their silver eyes and light-blond-to-white hair. A Claymore's standard abilities include overall enhanced physical prowess (most noticeably, strength), faster healing, limited shape modification and the ability to detect Yoma by sensing their Yoki (妖気, Yoki^?). To use their special abilities, they access the powers of their Yoma-half. However, if the Yoma powers of each Claymore are pushed over a certain limit the Claymore loses all humanity and becomes a powerful, highly intelligent, and incredibly bloodthirsty Yoma called an Awakened Being. A Claymore will ask a friend (usually a fellow Claymore) to kill them if they sense they are "Awakening", ensuring that they do not turn into the very monsters they hunt.

The secret organization is usually contacted by towns or villages afflicted by Yoma, and goes on to dispatch an appropriate number of Claymores to eliminate the target(s). Upon a successful kill, it then sends an agent to collect a large fee for its services. A town that fails to pay will never receive any further assistance, and will be left at the mercy of the Yoma. It has been insinuated that the organization itself sends Yoma to the towns that fail to pay, or at least inform the Yoma that said towns are no longer under Claymore protection. The organization is often strict and harsh; hybrids who break the rules (for example, by killing a human, even accidentally or to protect others) will be hunted down by their fellow hybrids. Claymores who cause trouble or Claymores suspected to be on the verge of Awakening will be sent on suicide missions without their knowledge. Various characters throughout the series suspect the organization of being much more sinister than it appears, though most are either unwilling or unable to act on the matter as it would mean conflict with other Claymores.

Despite saving humans on a regular basis, Claymores are often alienated from and feared by humans due to their incredible powers, their relation to Yomas, and generally aloof attitudes. Humans will often call them "silver-eyed witches/slayers" or "monsters". Family members of individuals impersonated by Yoma tend to be banished from villages for fear that they might be Yoma too. Claymores are often girls who suffered this fate or survivors of villages wiped out by Yoma. Presumably from one or more of their background, Yoma blood, their training, and their harsh lives, many Claymores are generally serious and at least outwardly cold. Claymores often live unhappy, lonely lives due to their solitary lifestyle and the knowledge that they will eventually die or become monsters. Some become hot-tempered and easily angered, while some other Claymores become bloodthirsty killers who enjoy taking life, more savage than the Yoma they hunt. Almost all of them avoid any sort of companionship with humans.