Shinji Kazama goes to Jindai High along with Kaname and Kyoko. Because of their common interests in AS and the military, he can be seen as Sousuke's best friend. He is also part of the Photo Club at Jindai High School.
In the episode "Lingerie Panic" he is seen stealing underwear from Kaname's apartment.
During episode 5 (Whispered) of Full Metal Panic! ( series 1), the English voice actor for Shinji, says 'Sasuke' instead of Sousuke when trying to announce that the latter was missing from the aeroplane.