A sushi chef’s knife is his life, he has few tools that are as important. The idea that a chef sharpens his knife daily is a testament to the importance of his tool. His knife must be razor-sharp, designed to cut in one movement for accuracy, a chef takes his line and cuts. If you look at the photo, you’ll notice that the finger position is key, away from the blade, I mean the cut begins while the finger is in a safe position. The chef’s knife is so sharp it could take the finger off before it’s too late to notice. The movement is one long cut, from the bottom of the blade through to finishing at the top of the blade so the finger is safe.
Japanese knives are historically single edges, beveled but on one side with the opposite edge straight. This knife is a takohiki shape and is used for certain cuts.
The straight edge gives way to a more precise surgical cut with Hippocrates being the first to describe the surgical knife. The Greeks strike again, he used the word macairion, derived from machaira. Therefore, even in Hippocrates’ time, the shape of the scalpel was much the same as it is today with one side straight.