here, i wiped up a quick drawing for you. i think it would be pretty cool if your ninja had some more "ceremonial" looking designs sown into his dark clothes. so, he can still be hidden in the dark, but he can look more intimidating in the light
i didnt finish it completely, but you get the idea. mostly blacks, dark grays, and very dark browns. with some dark reds and golds sown in as design.
and, on the strap across his chest, i think it would be cool to have a long line of symbols. i wasnt really sure what to put there, because i dont know if ur ninja is japanese, chinese, ect. so, i just scribbled there.
hope you like it