Chii

Chii is a human-like personal computer - persocom for short - who was found by Hideki Motosuwa in the trash on a street. Once she was activated, it was discovered that Chii had no operating system data, and the only thing she could say at first was "Chii". 

The android has a natural curiosity for anything new she comes across, often has trouble grasping even simple lessons, has difficulty differentiating right from wrong and sometimes does inappropriate things by accident. Chii strives to make other people, Hideki in particular, happy, and becomes easily saddened when she thinks she has done something wrong.