知佳

Chika is one of the identical twin "EXTRA" androids which were created by Ellen. Both she and and her sister Chito do not have any human feelings, they are designed to be used only as cold-blooded weapons. The two of them were created from Atsuko's genes.

It seems that the only difference between the twins is their hairstyles. While Chika has two braids, Chito has only one.