I can recommend Barry Lancet (he has written a few although the only title I recall is Japantown). Well-written and fast-paced but less formulaic than some. The author lives in Tokyo, I believe, so quite accurate in that respect. The Japanese characters are well-rounded and not just foils for the non-Japanese (half-Japanese?) hero.
Shibumi (Trevanian?) is a kind of classic in this genre (although it's not a favourite of mine). It's a bit old, but he wrote a follow-up which featured baji not so long ago.
Tan Twan Eng (The Gift of Rain, Garden of the Evening Mists) - these are literary fiction with extensive flashbacks to the Japanese occupation of Malaysia and both feature martial arts as integral to the plot (especiallythe first). Good writing, quite heavy, dealing with a variety of themes that I couldn't do justice to here e.g. betrayal, collaboration, friendship.
Yours truly also has a series (crime) I'm hoping to bring out later this year set in 1930s Japan. 1&2 are complete, but I want to get no.3 (80% done) finished before releasing them. Obviously, they will be worth reading, too
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Graculus
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