Angel Sanctuary Avatars

Setsuna Mudo is a problematic delinquent high school student, who is in love with his sister. To add to his problems, he is also a reincarnation of a fallen angel, which gets him caught in a messy war between heaven and hell.
The background story is that of Organic Angel Alexiel, who is one of the highest beings in existence, third only to God himself and the primordial man known as Adam Kadmon. She is, in rank, equal to her twin brother the Inorganic Angel Rosiel. Before the beginning of the series God has fallen asleep to "gather his powers" which indicates that he is, in this series, very powerful but not omnipotent.
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 slumbering absence and the weakening of their enemies the angels of heaven wage war on the Evil race (a group of beings that are 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 goes against Alexiel's morals. 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.