Elfen Lied

A supernatural system allows people to take revenge by having other people sent to Hell via the services of a mysterious entity and her assistants who implement this system. Revenge, injustice, hatred, and the nature of human emotions are common themes throughout the series.

Located in the center of a remote island, the Abyss is the last unexplored region, a huge and treacherous fathomless hole inhabited by strange creatures where only the bravest adventurers descend in search of ancient relics. In the upper levels of the Abyss, Riko, a girl who dreams of becoming an explorer, stumbles upon a mysterious little boy.

A species of parasitic aliens descends on Earth and quickly infiltrates humanity by entering the brains of vulnerable targets; insatiable beings that gain total control of their host and are capable of transforming themselves to feed on unsuspecting prey. High school student Shinichi Izumi falls victim to one of these parasites, but the creature fails to take over his brain and ends up in his right hand.

When a shapeshifting demon with a thirst for human flesh, known as "youma," arrives in Raki's village, a lone woman with silver eyes walks into town with only a sword upon her back. She is a "Claymore," a being manufactured as half-human and half-youma, for the express purpose of exterminating these monsters. After Raki's family is killed, the Claymore saves his life, but he is subsequently banished from his home. With nowhere else to go, Raki finds the Claymore, known as Clare, and decides to follow her on her journeys. As the pair travel from town to town, defeating youma along the way, more about Clare's organization and her fellow warriors comes to light. With every town cleansed and every demon destroyed, they come closer to the youma on which Clare has sought vengeance ever since she chose to become a Claymore.