Angel Sanctuary (天使禁猟区, Tenshi Kinryōku) is a manga written and illustrated by Kaori Yuki. It was serialized in Hana to Yume from February 1995 to February 2001. 20 tankobon volumes were published by Hakusensha, the first volume was releases in 1997 to 2001. The manga was adapted into a 3 episode OVA by Bandai Visual and Hal Film Maker; it was intended to be an introduction, not the whole story. It was originally licensed by Central Park Media, the OVA by Media Blasters. A series of drama CDs based on the other story arcs were also released. Angel Sanctuary is licensed by Viz Media for an English release in North America. The final volume was released June 2007.
In this series, Assiah (Earth) and the upper levels of Hell (Gehenna) are mirror images of each other. As mankind polluted and destroyed the Earth, the lands of Hell also began to weaken. Taking advantage of their creator's sleep and the weakening of their enemies, the angels of heaven wage war on the Evil race (a group of demons who have turned away from the Devil, Lucifer and God; they live in Gehenna and worship "Holy Dragon Gods"), wiping most of them out. In doing this the angels fighting the war are corrupted. They commit vile crimes and murders under the name of God and righteousness. This deeply sickened Organic Angel Alexiel. She feels that the Evils are more pure in their actions since they do not put up a charade of purity to cover their crimes. She joins the Evils' side of the war and declares an official revolt against God.
The war comes to a climax and end when Alexiel fights against her brother Rosiel. Earlier, Rosiel had found out that he is decomposing and that his mind will rot. He went to Alexiel to ask her to kill him before he goes crazy, which she agrees to. But when she is about to deal the killing blow to him, he yells: "Would you kill your own twin brother, Alexiel!?" She then is filled with pity and remorse, so she seals him within the Earth using a barrier of forbidden magic. However, in doing this, she used every ounce of her power and shatters Nanatsusaya (the "Holy Sword of God", that made every bearer before Alexiel go mad with its power and kill themselves and countless others). The result is that Rosiel is now sealed inside Assiah and Alexiel is captured and tried by the Angel of Judgment, Uriel.
For her crimes, Alexiel is sentenced to the most severe punishment given to the fallen: Her body and soul are separated. The body is frozen in an angel crystal and locked away in the deepest depths of angel security on the fourth circle/layer of Heaven, Machonon. Her soul is sentenced to be incarnated into a human mortal. That mortal's life is sentenced to be filled with physical and emotional pain. Every time Alexiel is re-incarnated, the cycle begins anew. But in every incarnation, Alexiel's personality is still present under specific (e.g. dangerous) circumstances, which causes her incarnation to have strange spiritual patterns and powers at times; it is as if the incarnation has a multiple personality disorder. In the storyline, she is incarnated into a boy named Setsuna Mudo. Setsuna Mudo is a problematic delinquent high school student, who is in love with his sister (thus producing the emotional pain required by her punishment). To add to his problems, he gets caught up in the complex war between heaven and hell.