Okay hihi ^_^
First off, I feel the layer still stands out too much, you should put C4D's, vectors, wireframes, etc, etc, over the render to blend it in. (Burn, Blur, Sharpen Tool can do that too

)
Second thing is I don't really think the background goes with render, but that's my opinion!
Third off is the flow should be coming from the right down to the left but there isn't anything to make it look like it's flowing D:
Fourth is that you should use soft brushes on overlay&lighten to make things more realistic, for example Naruto's arm on the right should have some light too it
Overall though, it looks alright

You're improving every sig you make

I hope you don't take this in a bad way, just some CnC