A leaked video from Tekken 6 reveals Kazuya’s EX costume is some kind of robo armor. (Thanks for the tip Jared!!)
Like the other EX costumes in Tekken 6, Kazuya’s mechamail was designed by a manga artist and it appears Takayuki Yamaguchi of Shigurui fame designed the outfit.
Kazuya with a robot look is eccentric, but not as over the top as Roger Jr.’s Cubone-like EX outfit.