I google image-searched Shinkawa, immediately knew who he was from the first images to load. If it's that style you're going for then you can add some shading with some painterly greys, and I agree with ant4given that you need to accentuate that jaw, maybe even make the whole jaw black with white detail lines? I feel we should be seeing some neck and shoulders with that white space underneath. But I assume you were going to do that anyway. Other than that, really good so far, I like how you've done the hair.