Hmm...I know this is fiction, but...When does this take place? There weren't really any Okinawan members of the Buke (Samurai class)--in fact the ownership of weaponry on Okinawa carried a pretty harsh penalty. Thus the creation of "undercover" weapons like the Sai, Jitte, and three-section-staff (which, for the life of me, I can't remember the real name of).
However, the writing is damn good, and I would like to see more.