3x3 Eyes (or Sazan Eyes, in Japanese) is the story of a girl named Pai and her close friend and "Wu", Yakumo. By outward appearances, Pai appears to be no more than 16 years old, but she has actually been alive for over 300 years. She is one of the sole, surviving members of an ancient mysterious race, the Sanjiyan Unkara (Three-Eyed-Ones). The Sanjiyans are beautiful, extremely long-lived creatures who are capable of consuming one soul and merging it with their own. Pai, however, has no memory of her past, only that she has one goal: to become human. By all outward appearances, Pai appears to be a normal girl, with a bright, happy, personality. Most of the time, she seems unaware of her dual personality...
*taken from the Anime Archive