It's fantastic, but she isn't really Karin... and i tell you why. Karin should have brown eyes, not blue. And her eyelashes should be a little more long and visible. Her face is a little too masculine. Finally there's something strange with the hairs behind her forehead, given the point of view and how they bend they are very close to her face, which in my opinion is not exactly how she is.
Besides all this, the pose seems a little unbalanced to me, i mean not from an artistic point of view, but from a fighting point of view. She seems to have lost the equilibrium and she's going to fall.
Last remark: hey! I wanted a background!
Anyway, amazing colors and great work on the whole.
Well, I didn't see that coming. It's interesting to see the different coloring styles each artist has - I'm just starting with PS and it's really inspiring to see so many different results come out of these programs.