Origin
Although she looks like a normal teenage girl, Pai is actually the three hundred-year old, last surviving member of a mystic race called the Sanjiyan Unkara. These three-eyed beings had life spans of thousands of years and possessed great supernatural powers, not least of which is the ability to grant immortality to others. As using their destructive abilities can be exhausting, the Sanjiyan created immortal protectors for themselves by taking the souls of other beings and merging them with their own.
Pai herself was found wandering alone in the mountains of Tibet by an archaeologist named Fujii, who promised to help her fulfill her childhood dream of becoming human. Though he died before he could help her, Fujii sent Pai to his teenage son Yakumo, along with a note passing the obligation onto him. While Yakumo resented having this weight thrown onto his shoulders out of the blue, he agreed to help Pai after she saved his life from a fatal injury by absorbing his soul and making him immortal. After a failed attempt to resume his normal life, Yakumo and Pai set off together on their quest to become human.
Personality
Alike many Sanjiyan, Pai has a split personality, though at her stage there are only two personalities. The most commonly seen one is Pai, who is childish, naive and gentle-hearted, but doesn’t know how to use her powers, and is usually active when her third eye is closed. The other personality is usually referred to as “the Sanjiyan”, though her name is later revealed to be Parvati the fourth. This identity has full access to their powers but usually comes across as cold-hearted, severe and arrogant, and is wholly unimpressed with Yakumo as a guardian. Over time Parvati is revealed to be kinder than she at first seems, though also somewhat less mature.
While Pai fervently wishes to become human, she has forgotten why. She also doesn’t speak Japanese fluently, though oddly, her Sanjiyan alter ego does.