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you can make your life much easier by taking the kamisori to 8k (or 5k if really needs work) and then go to the Jnat.

That is not certified Koma, it is stamped as such but not Asano stamped, it may or it may not work well. Authentic Koma are inspected for purity and Asano stamped.

In general no, they vary in quality as any other Jnat so you may have to go trough a few till you find one that you like. Therein lies the issue, they are rare (the Asano stamped ones) and expensive....