Hello Shinichi,
I hope you and your family are fine and everything is on the right way.
Here some impressions and experience about the knife.

- Professional Kurouchi Santoku knife with a 165mm blade
Personally I love the unpolished blade. You can see marks from forging and the colour of tempering and so you can get an imagination of the great craftsmanship to build this knife.
As you can see that isn't an industrial mass product. An unique item. It's your knife!
As a result of the used steel and the production process you get a knife with a blade that has a high hardness. Higher then typical European blades has.
The effect: great sharpness and a long lasting edge.
I resharpened it after a week of commonly using. But only a few moves on a water stone was enough and after I used a leather strop I got a shaving razor sharp edge. Great!
The handle is very comfortable and easy to maintain. As the handle isn't symmetrically my wife as an left-hander has no problems to use the knife in a precise way.
The knife is surprisingly light, so it's good for tireless work.

Conclusion:
The best knife I ever had. Fine to handle, very sharp, easy to resharpen and long endurance of sharpness.

Weakness:
only once: I have to fight with my wife for using the knife!
;)

So let's go for the next knife;)