Well there's Trevanian's _Shibumi_ --- it hasn't aged well, but has a certain '70s charm.
Agree that anyone interested in Japan should read the fictionalized Musashi books (and _The Book of Five Rings_, and the _Hagakure_, &c.)
When I was a kid I found a couple of books by T. C. Rypel, about a half-white Samurai, Gonji --- the first book was _Deathwind of Vedun_ (I think I had the second and fourth book) --- always meant to find the balance of them.
I've always been fond of _The Cybernetic Samurai_ by Victor Milán --- you pretty much need to read Heinlein's _The Moon is a Harsh Mistress_ first (and Minsky's _The Turing Option is a good grounding / contrast) though.
Kara Dalkey's _The Nightingale_ moves the setting to Japan from China and is as well done as the other ``Fairy Tale'' novels.
Neil Gaiman's _Sandman: The Dream Hunters_ is set in Japan and is quite vivid and moving.