Age: 22
Birthday: September 21
Sign: Virgo
Blood type: AB
Height: 181 cm (5'11)
Weight: 69 kg (153 lbs.)
Hair: Brown
Eyes: Green
Hobbies: Drinking

Despite his pleasant and calm outward expression, Hakkai is a demon not to be reckoned with. He is capable of channeling his chi into powerful bursts of energy in battle, and can also form it into a shield to protect himself or his friends. He wears three ear cuffs that are his limiters. When removed, his true power is released. He can often dispatch demons much larger than himself or numerous foes in this form. Hakkai is often reluctant to do so due to the possible danger to his friends. Hakkai is the member of the four journeying with Sanzou that tends to mother the others [for lack of a better term], cleaning up after them, shopping, etc. The jeep that the group of four is driven in by Hakkai is actually his small magical dragon companion, Hakuryu.

Long before the journey to the west, Hakkai was known as the human Cho Gonou, an orphan who later met and married his older sister Cho Kanan. He was a teacher in the village that they later lived in together. One day, Gonou returned from work to find that the townspeople had given his wife as an offering to the centipede demon Hyakuganmaou because they saw her as the most expendible of the women, being without relatives. Enraged, Gonou slaughtered a large number of townsfolk before journeying to the demon's castle. There he killed every demon he found single-handedly. Coming upon the imprisoned Kanan, he wanted to free her and take her home with him. She informed him that she couldn't leave with him, since she had been raped and impregnated by the demon king. Using Gonou's blade, she killed herself in front of her husband.

The distraught Cho Gonou was come upon by the remaining son of Hyakuganmaou, Chin Yisou, who attacked him, slicing his belly. Wanting to find out whether or not a tale that he'd heard was true, Chin Yisou dripped his own blood into Gonou's wound. Having now bathed in the blood of 1,000 demons, Gonou became one, killing Yisou before leaving the castle.

The wounded Cho Gonou was saved physically by the half-demon Sha Gojou, and spiritually by Genjo Sanzou, taking the new name Cho Hakkai as a symbol of his rebirth. He and Gojou became very good friends due to their experiences together before the journey to the west. Many times, Hakkai still reflects on his past pain, and his memories of Kanan are bittersweet.

In his previous life, Hakkai was a god in Heaven. He was known as Field Marshall Tenpou, an eccentric military man who was fond of his library of books, many of which were about the world below. He could often be found with his nose in a book [or buried under them] in his library. He was the friend of Konzen Douji as well as his subordinate General Kenren. He and Kenren were fairly inseparable and had an easy-going relationship despite their difference in rank. Their soon to be enemy Li Touten [father of Nataku], referred to Kenren as Tenpou's 'husband' at one point. Although Tenpou tended to be mild-mannered, when provoked he was not to be taken lightly and would fiercely defend those that he cared about, qualities that he carried over into his next life. The god's weapon of choice was the katana.
(Source: Saiyuki Fansite, Saiyuki Wikia)