The knives I collect are all masterpieces of Japanese art and craft. Exeptional skill is required to make them. To just put them on display would be a pity, almost a crime. It's like collecting Ferraris without ever driving them. So, I extended my culinary journey and started experimenting with sushi and sashimi. In addition to being a lot of fun and very tasty, it is also the perfect way to find out how the knife performs after sharpening. It is not always enough to get a knife sharp.
A yanagi can be incredibly sharp and still be a poor performer on sashimi. The finishing, edge shape and grind can have huge impact on cutting performance. A totally flat, mirror polished bladeroad, for instance, is often useless, as the thin fish slices sticks to it and gets torn up.
To my experience a pronounced hamaguriba, or clam shell shape, on the edge and lower part of the blade road combined with a blade road finished to a #3000-6000 grit works best, by releasing the fish slices easily. The cutting edge should still be polished with a very fine finisher higher than #10000 and be razor sharp.
Below picture shows an early attempt on nigri and maki sushi. I am especially happy with the salmon slices, as I managed to get almost identical pattern on all. Luck? No, it's Shigefusa! :oD