This is sooo pretty. I love Kairi's expression, her hands, the Heartless, and the colors the most! I agree with the others about proportions. In addition, I feel that the shadow on the right side of her face is really distracting. I'm not sure if it's a cast shadow or a form shadow, but either way I think that it could be either a little thinner or more blended?
Overall, this is amazing. I hope you post more of your work in the future! c: