Angel Sanctuary is both a 20-volume manga series drawn by Kaori Yuki (由貴香織里) and a 3-episode OAV anime based on this manga. The original Japanese title is Tenshi Kinryouku (天使禁猟区). The manga was published by Hana to Yume Comics, and the anime was released in Japan on DVD in 2000 by Bandai Visual and in the United States in 2001 by Central Park Media.
The artwork is dark and brooding, hauntingly beautiful, and filled with winged bishounen, reminiscent of CLAMP's X or Tokyo Babylon series. The story deals with a number of potentially controversial issues, such as heaven/hell, the nature/existence of angels, and incest, as well as having many of the main characters look or act or somehow be the opposite gender from what they really are (this makes sense even after just seeing the OAVs). Unfortunately, the OAVs do nothing more than illustrate the very first part of the story, then stop at something of a cliffhanger where the main character Mudou Setsuna has to make a huge choice. Perhaps this was an intentional way to induce more people to buy the manga, but since as of this writing the manga has not been officially translated into English, non-Japanese speakers who want the rest of the story are out of luck unless they want to buy the Japanese volumes and find a fan translation online. Because of this, the story in the animation seems very unfinished and compressed, as if they wanted to fit the entire 20-volume story into just three episodes, but really could not manage it and therefore decided to just release what would fit. Taken as a prologue to a much larger story, it makes more sense, but still leaves the viewer with a feeling of incompleteness.
Mudou Setsuna/無道殺那 (voiced by Kojima Kenji): The main character of the series, Setsuna is the current human reincarnation of the (female) angel Alexiel. His love for Sara inhibits Alexiel's awakening within him. Similarly to Kamui in CLAMP's X, the fate of the world (the angels' world, anyway) rests on his choices, but he just wants to be left alone with his love. He is constantly getting into fights with bullies at his school, but the sight of blood makes him faint, preventing him from ever actually killing anyone.
Mudou Sara/無道紗羅 (voiced by Kawasumi Ayako): Setsuna's sister, and also in love with Setsuna. Her character is similar to Monou Kotori in X, in that she is in love with the main character but does not carry power herself. She is much more strong-willed than Kotori, however. She was raised separately from Setsuna after their parents divorced when they were children. Her mother hates Setsuna and tries to keep them apart.
Alexiel/アレクシエル (voiced by Orikasa Ai): The "organic angel," one of the most powerful angels, she tried to rebel against God and was imprisoned in the Angel Crystal for centuries. While her body is imprisoned, her soul is continually reincarnated into humans who die painfully to punish her. She is currently reincarnated into Setsuna.
Rosiel/ロシエル (voiced by Chiba Susumu): The "inorganic angel," Alexiel's twin brother, also in love with Alexiel, who is not in love with him. He was imprisoned on Earth by Alexiel before her imprisonment and broke free with the help of Katan.
Katan/カタン (voiced by Miki Shinichirou): One of Rosiel's followers who helps him break his imprisonment.
Kurai/九雷 (voiced by Miyamura Yuuko): One of the demons from the country of Gehenna, which was destroyed by the angels taking advantage of its weakening caused by pollution mirrored from that caused on Earth by humans. Close friend of Alexiel and is trying to free Alexiel from her imprisonment.
Arakune/紫羅九音 (from Arachne) (voiced by Asano Mayumi): "My heart is that of a female but my strength is male." Saying this in the first volume of the manga, he ends up sounding like Nuriko from Fushigi Yuugi. He follows around and protects Kurai, his cousin.
Kira Sakuya/吉良朔夜 (voiced by Koyasu Takehito): Setsuna's friend from school who comes to his rescue in fights and generally acts like an older brother to Setsuna.
Katou Yue/加藤故 (voiced by Ueda Yuuji): Sakuya's friend from school who becomes entangled in Rosiel's plots.
Adam Kadamon/Serafita/セラフィタ (voiced by Nakao Ryuusei): The ultimate angel who is said to possess powers neither of light or darkness. Neither male or female, it is the one who gives Setsuna a choice at the end of the OAVs.
Volume 1 of the manga