The only thing that bothers me about the face is the nasolabial fold which I think goes down too deep and is throwing off the form of his lower face a little bit.
Besides that this is looking sweet, man

Are you going to be adding a mask or that hood thing? That will be the most explicit thing you can do to make it clear he's a ninja. Keep it coming, man.

(btw, I'm a fan of your last several entries. Good work!)