You know what works pretty well for samurai sound effects? Trust me on this ive done it before. First, get any DVD or video of any of the Lone Wolf and Cub movies (they have tonnes of classic samurai sfx). Then play it and just record the sounds you want as wav files to your computer - which you can use later in your movie. Even audio recording from a VCR to a computer like 2 metres away will work pretty well if you have the sound turned up. I did it with Creative Wav Studio and edited it in Adobe Premiere with my movie and it seemed to work pretty well.
It may take a little while to get all the sounds you want, but trust me you can get a whole range of cool sounding shit. Sword slices, arterial sprays, sword hitting flesh, sword clanging against sword, etc. Anything you’d need for your ninja/samurai movie.
