Pai looks like an ordinary girl, but she's not. She is actually a 300-year old Sanjiyan. The Sanjiyan are a legendary race of powerful, immortal creatures with three eyes. But Pai just wants to be an ordinary human being. She searches for Yakumo Fujii, the son of an archaeologist who devoted his life to learning about the Sanjiyan. After a string of weird events, Yakumo agrees to join Pai in her quest, and the two soon find themselves entangled in a web of opposing occult forces. It seems Pai and Yakumo are not the only ones who are after the "Statue of Humanity"... to complicate things further, Pai isn't aware she has two very different personalities!

From http://www.animetric.com/123/3x3.html