I. Want. To play with Riku's hair. Or at least touch it. If he were real he'd probably kill anyone but Sora if they touched his hair. I don't think any drawing has made me want to do that before. But you did an awesome job on the hair. It's clearly the emphasis to me.
I love how you've done Riku's profile, but [excuse the art student critique..] if you look at how small it is and then look at how high up his hair goes, you'd realize how huge his head must be under all of that hair. It's just something I noticed about the scale/proportions in this piece, and I felt the need to point it out.
I realize that this effect could be intentional, and that it may be your style, but I think it's something to keep in mind. Perhaps next time you could bring the top of his head down, or make his profile bigger. The way you've drawn this, however, is fucken awesome. And I love it.