Kaji has very important job in NERV. Unfortunately we are never TRULY told what his job is. He is also a spy for SEELE. He kidnapped Fuyutski so he could be interrogated. He and Misato were former lovers a few years back and Kaji constantly flirts with her and still loves her and we see signs that Misato feels mutually about him. He came over with Asuka and EVA-02 from Germany. Kaji actually is an important character to the series. He was the one that convinced Shinji to save Tokyo-3 after he quit NERV. He also brought Adam with him. Asuka is in love with Kaji because "You can depend on him." and she thinks he is cute. She constantly flirts with him trying to get his attention. He also has a secret hobby of growing watermellons. Kaji was killed by an unknown person after returning Kozo to NERV. Kaji's final comment was "Your late." Everything goes black and we hear a shot. Some speculate it was Misato but I don't buy that crap. I go by justifiable evidence... not speculation. Maybe Kaji survived, maybe he shot whoever was there... we can never be sure. He left a message on Misato's machine telling her he loved her and finally you get the true essence of Kaji.