Kaji Ryohji

Kaji Ryohji, a charming, flamboyant man, he is not easy to categorize. He was part of the German team that took care of Asuka and returned to Japan with her and Unit-02.
Ryohji was Misato's lover at University. He is easy with women, always flirtatious but somewhat dark and introverted as well sometimes.
He seems to hold an important position in the dealings of NERV but one never gets to know what his job there really is. In fact, Kaji worked for all sides, double-played for SEELE as well as for NERV and performed his own researches in between.
The interesting question is : Who shot Kaji ? And why ?