After seeing all the different kinds of relationships that humans can have with persocoms, Hideki realizes that Chi is so much more to him than just a fancy piece of computer technology. Hideki finally learns the secrets behind Chi's mysterious past, as well as the great power that she possesses—a power that poses a threat to all persocoms. With the fate of all persocoms lying in the balance, Hideki must finally answer: what does Chi mean to him, and can the two of them find happiness together?

Chobits 20th Anniversary Edition, Volume 4, by CLAMP.