Chi (or Chii) is a character from the manga and anime series Chobits, that also appears in the series Tsubasa: Reservoir Chronicle and Kobato.
She is a Chobit (a persocom or personal computer) created by Ichiro Mihara.
The name Chobit comes from her creator who called anything "small and hopelessly adorable" Chobi.
So two Chobi, Chi and her sister Freya, became "Chobits".
Chobits - Persocom (Vol. 1)
