3x3 Eyes

Plot Summary: Through a strange series of events, a young man named Yakumo Fuuji becomes the immortal slave of the last of a race of 3 Eyed immortals. The immortal, Pai, absorbs his soul to save his life, making him immortal in the process. Now, he begins a journey with the female immortal in an attempt to find a way of becoming human. Of course, there are many complications along the way, not the least of which being that the immortal is a female with a split personality, one achingly cute and the other being no-nonsense destructive power, and romances that develop between.

DO NOT and I mean do not read it if you're err..religiously inclined. 40 volumes worth of emotions, fights and more fights with the usual endless battle between right and wrong.
I'm using spoiler mode right from the start because I am not going to describe the contents but rather I'll tell you what characters (name wise rather than exact appearance) show up in there.

Spoiler:

That's about all there is, or all that I can remember. The series is good save the huge and insane fights. The Wu being immortal is subjected to a lot of mutilations and more often than not you see them firing off blasts or summoning demons even though they are just half-bodies with the entire spinal cord hanging below. Damage is extreme, bloody and gore. For most the fights involve Benares, Kaiyanwang/Shiva's Wu. He's a formidable opponent who summons powerful beasts and the one unexplained but mostly used concept is this - When a Sanjiyan Unkara is in mortal danger, his/her Wu receives unlimited power. A good read but a very long series especially with the useless fights seeing how most of it is with Benares.