Seriously love your work. I think the sketch of mugen was nearly spot-on, by the by :)
Fuu, on the other hand is 85% spot-on... But the eyes feel a little too intense for her character. They're generally softer and (even when she's perturbed by something) definitely show her age.
This is splendid, nonetheless. It's also neat to see you're a fan of samurai champloo.