Nagisa Kaoru was sent directly to NERV Headquarters, as the replacement of Souryu Asuka Langley, for the pilot of Eva-02. He was referred to as "The Fifth Child". Due to unusual synchronization data, Kaoru was found to be the 17th Angel. When he first came, he became friends with Shinji. Unfortunately, when Shinji found he was an angel, well nevermind you'll have to watch it yourself.
Once when he approached Ayanami Rei, he said that she was the same as him, and Rei seemed to agree with him. Does it suggested that Rei is also an angel?