Ayanami Rei is the expressionless character from Neon Genesis Evangelion.
She is the First Child (First Children in the Japanese version), pilot of the Evangelion Unit-00 and one of the female main characters.
Rei is the favourite Eva pilot of Gendo Ikari as she follows her without question.
The reason why she acts so is because she is a clone of Ayanami Yui and lacks of emotion in her system.
Everytime Rei got absorbed by an EVA, a new clone is build instantly to replace her.
Ayanami Rei requires 4 sheets of paper to build