She is a genius cyberdoll said to have an IQ of 50,000 in human terms. Kei is originally given the mission of formulating a strategy to get May back. She becomes interested in Kazuya after hearing how he regards cyberdolls and changes her mind. Kei's memory bank of facts is extensive, but she often takes a while to process information that is more abstract. At times, abstract or philosophical questions can cause her CPU to lock up.

Spoiler

She later forms a crush on Kazuya and takes up residence in his closet.

(Source: Wikipedia)