Though the character looks simple, the design appears complex with your rigorous shading techniques. There are few people I have seen that are better at shading eyes.

The clothes look pretty good, but the armbands look just a little bit flat on Hastune's left arm, but otherwise, you did very well.

The pose looks pretty realistic; you have made a difficult pose look easy, much how a good musician makes difficult songs look easy. The character designer for Vocaloid's character would be proud.

Your hair coloring skills are nothing short of fantastic. They are quite the sight. The fading on the right and the winter-like feel make this an interesting piece.

One thing I noticed: She doesn't have a neck?

The thing I can't be more thrilled about is the shading. Continue this style in future works and you won't be sorry.