Aritsugu in Kyoto is the best known knife shop in Kyoto. I have been shopping there for thirty years and their quality has diminished over time with a focus on being more commercially successful. Their cash only policy can be annoying for foreigners despite the fact that they are catering mostly to westerners, it seems odd. On top of it, selling them impractical knives that rust almost instantly after use, I wonder why this shop is so popular.
In fact the double edge blades are very difficult to care for, and if you acquire one, you must note that it will almost definitely rust. Getting the rust off is not as easy as you think even though they provide instructions with each knife.
Lastly, try to sharpen their knives and that is another challenge.
This video was taken at Aritsugu in Kyoto and the staff sharpen a typical double edge knife.