Rei's brain is comprised of 60 smartphone motherboards, filled with useful information regarding astronomy, astronautics, earth science, and a surprising depth of knowledge about Evangelion and Shonen Jump characters. Rei lacks common-sense programming and basic human biology info, such as average human lifespans. Rei has no ability to lie, and no concept of what is appropriate and inappropriate to say in a conversation. Rei is faithful, thoughtful, highly determined, resourceful, and inventive.