自古妖魔侵入人类的世界，化作人形并以吞食人类的内脏为生，对妖魔束手无策的人类唯有求助于身背巨剑的女性战士们。因为战士们是由于体内混合了妖魔的血肉才得到超人的力量，所以人类同样将她们视为异类，一方面依靠着她们斩杀妖魔，一方面畏惧并排斥着她们，并将她们称为“Claymore（大剑）”。 当妖魔的出现打破了一个普通山村的平静生活，万般无奈的村长只好求助于大剑组织。一位面容冷酷的战士接受委托来到这里，由此拉开了这场波澜壮阔的故事序幕。

The Diclonius, a mutated homo sapien that is said to be selected by God and will eventually become the destruction of mankind, possesses two horns in their heads, and has a "sixth sense" which gives it telekinetic abilities. Due to this dangerous power, they have been captured and isolated in laboratories by the government. Lucy, a young and psychotic Diclonius, manages to break free of her confines and brutally murder most of the guards in the laboratory, only to get shot in the head as she makes her escape. She survives and manages to drift along to a beach, where two teenagers named Kouta and Yuka discovers her. Having lost her memories, she was named after the only thing that she can now say, "Nyuu," and the two allow her to stay at Kouta's home. However, it appears that the evil "Lucy" is not dead just yet...

An untold chapter in the Mass Effect saga, following the early career of Alliance Marine, James Vega, as he leads a squad of elite special forces into battle against a mysterious alien threat known as The Collectors. Stationed at a colony in a remote star system, Vega and his troops must protect the inhabitants from an invasion of the deadly insectoid warriors determined to collect the population for unknown purposes. Soon after the attack, Vega's commanding officer falls in battle, forcing the young officer to embrace the responsibility of leadership for the colony's survival. Having idolized Earth's greatest hero and warrior, Commander Shepard (the central character in the Mass Effect video games), the young and idealistic Vega must now make life and the death decisions that will effect not only the lives of his squad, but the lives of every person in the colony - all of whom he has sworn to protect...