Characters:
Pai
Meishing
Li Rin Rin
Shunkai
Choukai
Asai Natsuko
Yakumo Fuuji
Mama
Shiva
Steve Ron
Houasyou (Enchanted Snake)
Tatsuya
Benares
Pai
Sweet, Cute Little Airhead Pai from Tibet is really what made Yakumo look twice at her, and in doing so spends the latter half of his time taking care of and protecting her. Pai seems only to have the intellectual capabilities of a little girl; she is sweet, kind, innocent and unworldly, yet she too is able to call up certain monsters to her aid, not because she had defeated them but more because they were touched by her compassion (somehow). It was her kind nature and innocence which turned many enemies into friends throughout the course of their journey.
Meishing
Younger sister of Steve Long and a superb martial artist. She becomes involved in story when she witnesses her brothers apartment blown up. In the rubble she finds a piece of the statue of humanity. She begins to search for her brother and those who bombed his apartment. This is when she runs into Pai and Yakumo. At first she bashed up Yakumo. She falls in love with Yakumo, but ended up studying as an exchange student in England when it became obvious Yakumo was only interested in Pai.
Li Rin Rin
The editor and manager of the Yougekisha magazine and company (who promotes the belief of ghosts and demons though she is skeptical), which is a ghost-busting squad who gets paid to cleanse the streets from all manners of evils. Rin Rin originally intended to exploit Yakumo's and Pai's abilities, but she eventually aided Pai and Yakumo in their quest as Yakumo's boss and providing a HQ from which he can work from. She never misses an opportunity to wring every cent from some unfortunate person who stumbles across their paths, though.
She had worked with Yakumo's father and was in possession of the statue at the beginning of the series before she knew of its importance.
Shunkai
She is actually a "low status" demon which had assumed the shape and identity of a dead business woman and possessed by the demon Hsunkai, and had intended to make herself Kaiyanwang's Wu from the very beginning. She is responsible for the disappearance of Chin Aguri. Acting on Parvati IV's dissatisfaction with Yakumo, she eventually persuaded her to try to become the next Kaiyanwang. Being filthy rich, she becomes the financial supporter of the Yougekisha, and for the five years Pai and Yakumo had been with her she had been waiting for a chance. Her plan is foiled when Yakumo finds out, but she was deeply touched when he spared her life, and actually dies saving Yakumo from Benares.
She is aided by a few loyal followers. In demon form, she has talons, a tail and a single horn, and her breath can turn living flesh to stone (the effect lasting until her death).
Choukai
A Chinese man who, under Benares' direction, is also looking for Konron. He wishes to destroy the gate at Konlon to the Seichi so that Pai might not regain her memory and Kaiyan Wang can take over the world. He commands Ran-Bao-Bao and other monsters, eg. Naoshikai (Brain-eating Demon). He knows how to use magic circles and magic (paper) talismans. Choukai has a special power which he can use as a last resort.
Asai Natsuko
Yakumo's friend from junior high. Even when she had left school and was working as a highschool teacher, she never forgot about Yakumo. She has a crush on Yakumo. Natsuko is repeatedly taken over by Chui Tao Shi, or the Gesu (lower being), throughout the "Curse of the Gesu" series.
Yakumo Fuuji
The Wu of Parvati/Pai, this poor guy has no choice but to accompany Pai on the never ending quest for humanity. Yakumo starts off pretty helpless at the beginning when he had to fend off creatures already preying on his immortality and Pai, having had his head blown off and body parts severed (yep, it's gory). However, in the space of the four years after that he (fortunately) acquired some martial arts and some "magic" called Shuumashutsu, which involves calling up certain "monsters" (Shuuma) to his service which he had defeated before. You have to see it to understand it (sort of). Though Parvati is unimpressed with Yakumo's performance as her bodyguard, he eventually does prove himself to be a very good Wu though later in the Manga (much later).
Mama
The gender of Mama is unknown, but he is the owner of the gay bar Yakumo works at called the "Culture Shock", so I think it is safe to say that it is a he (his appearance can be either). When Shiun Kai dies, he undertakes the position of Yougekisha's financial supporter, and happens to be the only person who does not behold Yakumo's status in awe. Being never alarmed at anything, he is the one who wakes Yakumo up to reality and that being an immortal is not as fun as he first thought it was.
Shiva
The Kaiyanwan is the ruthless tyrant of the Triclops, and was known to have extremely long life as they suck the energy from other powerful Triclops when their powers weaken. Shiva is the second Kaiyanwan, and was originally a benevolent and even-tempered Triclop (it's hard to imagine). He brought up all the Parvatis, including Parvati IV (Pai) and was consequently engaged to Parvati IV (somehow), but when he became Kaiyanwan II, Parvati and the remaining Triclops used all of their power to bind him to a magical stone, called the Seimaseki. Since then, 300 years had passed and the seal had weakened, and soon Shiva will be able to terrorize the world again.
Steve Ron
Steve is the older brother of Meishing and a reknown Hong Kong exorcist; it was he who had gotten hold of the ningen no zou first which got him kidnapped. After being rescued by Yakumo and Pai, he came to work at the Yougekisha and ended up being partners with Li Rin Rin. He sometimes wears Taoist robes, and is occasionally referred to as Long Dao-Shi (Taoist monk Long). Also gives Yakumo "some not-so-useful romantic advice".
Houasyou (Enchanted Snake)
Houasyou is the beast used by Benares to perform Choang-Rin-Rin on Pai. In so doing, Houasyou apparently lost her memory, and was thus unable to carry out Benares' will. When Choang-Rin-Rin was expelled from Pai, the Sanjiyan was able to reincarnate Houasyou as Pai Ayanokouji, the girl who (with Houasyou's memory, but Pai's body) lived a life of her own in the years that Yakumo was looking for her. At the end of 3x3 Eyes volume 7 OVA, we see a young girl by the name of Ayanokouji Yoko lying in a hospital bed. This is really Houwasho. Pai gave Houwasho her body. However, there is one drawback to all this. When Houwasho comes in contact with water she transforms partly into an amphibious life form. And as an added bonus, she also has a thing for Yakumo. Imagine how that makes Pai/Parvati IV feel...
Tatsuya
One of Yakumo's friends. There really isn't alot to say about him because he doesn't really do too much in the anime or manga. He is the second tallest out of Yakumo's friends. He also knows some things about being a mechcanic.
Benares
Benares is Shiva's Wu, and at least 320 years old, and his true form is the incredibly evil Ryuushin (the dragon god) who acquired his human shape by hanging around the Seichi (the home of the Triclops) and eating Triclops. He became known as a great sorcerer, and had a pupil called Madourai, who turned against him for personal reasons and binded him to the earth. Along came Kaiyanwan II Shiva, undid the seal and turned Benares into his Wu. For the past 300 years Shiva was sealed, he had protected the Seimaseki and commanded a big following of evil creatures who believes their time will come when Shiva resurrects. Benares' powers, as one can imagine, is way beyond Yakumo's, yet he still regarded Yakumo as his greatest enemy. (Benares is the name of a town known for intense Shiva worship, located south of Nepal on the River Ganges, in India.)