Beware of the Mascara Ninja!
Nice job on this one. I like how you drew him in some kind of semi-realistic way. Almost like you "borrowed" some cartoony features and even anime style hair.
I think the serious facial expression looks good on him.
The texture on the ninja suit was a nice choice, but I don't like how it is just plain and does not change on the arms or generally does not follow the ups and downs of the body. Though I know this would be a pain to do it all correct, but I still thought I should mention it.
The anatomy on the body is very well done and I take it, the anatomy on the head is a bit more anime-ish on purpose, since it goes rather well with the hairdo.
And finally I also like the background and how you still made the actual char stand out from it even though it's grey too.
Good job!