The first shape we would like to introduce is the Nakiri. Japan absorbed a great deal of culture from China, and the use of the cleaver came with it. But because resources were limited (to put it plainly, the country was poor) owing to its island geography, the Nakiri became a scaled-down, lighter version of the Chinese cleaver. Japanese food was also largely vegetarian, following Chinese Mahayana Buddhist practice: livestock was not farmed for consumption, and meat came only from hunting, so meat rarely appeared at the table. A knife smaller than a cleaver therefore suited the cooking even better, and the Nakiri remained popular in old Japan for a very long time.
The meat Japanese people eat most today is fish. It spread widely during the Edo period, when sushi grew in popularity because sea fish could be transported into the large cities far more easily.
From the development of transport in the modern era, the Japanese moved from the fermented fish once used to make sushi as a means of preservation to fresh fish, for better flavour. That was only the beginning of modern sushi, however; the techniques and methods were still far from what they are today. Knives played a very large part in the sushi-making process. The oldest surviving historical evidence traces the knife Deba to a mention in the Edo period, where it is defined as a knife for preparing fish.
Deba is used to break down a whole fish into large, bone-free fillets. The Deba is a thick, stout knife with a heavy spine that transmits force well. It is single-bevelled (the grind runs from the spine down to the edge on one side only, while the other side drops straight down at 90 degrees from the spine to the edge). Because the Deba is used with a sawing motion into the fish, a medium level of sharpness is appropriate (around 1000 grit); there is no benefit in going finer, since the work does not rely on the edge to slice. On the contrary, an over-sharpened edge is a drawback, because breaking down fish sometimes means meeting hard parts, and too fine an edge will chip easily on impact.
The Yanagiba is the opposite: long and tapered, with a fairly slim blade and a single bevel (the grind runs from the spine to the edge on one side only, while the other side drops straight down at 90 degrees from the spine to the edge, just as on the Deba). The Yanagiba is the last knife to touch the fish, slicing it into bite-sized pieces, and it relies on the edge being drawn through the flesh. Besides needing an excellent edge (around 4000 grit and above), the blade must be long, because the cut depends on the length of the draw: removing skin, trimming the fillet, slicing the fish thinly, and so on.
During the Meiji period, when Europeans came to Japan to trade and to spread their religion, their food culture was absorbed as well. Because European dishes contain a great deal of meat, almost every European kitchen knife has a pointed tip.
Whatever the Japanese absorb from abroad, however, they adapt to their own culture. The Nakiri was therefore reshaped with a pointed tip to suit the newer cooking with more meat in it. A sharp tip is good for cutting through skin and the tough membrane on meat, while the blade stayed as thin and keen as before. Santoku, which can be rendered as "three virtues", refers to working equally well with meat, vegetables and fish; it is a genuinely versatile knife and has been the favourite of home cooks ever since. There is also a knife called Bunka, meaning "culture", which came about in exactly the same way as the Santoku: with the arrival of Western eating habits, a knife that could handle Western cooking too was needed, so the words "knife" and "culture" were joined together. The Santoku and the Bunka can be called the same knife, although some brands distinguish between the two names (Global, for example).
The knife European chefs use most is the chef's knife, and the Japanese adapted that to their own cooking culture as well. The chef's knife was made thinner and became the Gyuto, because everything in a Japanese kitchen must be delicate. A Japanese knifecuts with a push-and-cut motion (lifting the knife and letting the edge cut down into the food), whereas the Western technique uses a rocking motion (keeping the tip on the board and pressing the rear of the blade down onto the food, cutting through by pressure). The blade shapes differ accordingly: the Western chef's knife has a curved edge to suit the rocking motion, while the Japanese Gyuto has a noticeably thinner blade.
Usuba (usuba) is basically the same shape as the Nakiri, but what sets the Usuba apart is that it is single-bevelled. Part of the point is a keener edge, but the lighter weight makes it less suited to very hard vegetables such as pumpkin. The Kanto-style usuba is square-ended, while the Kansai style curves down to a point, giving it a tip that can be used for delicate work — though that tip breaks or chips easily. Compared with the Deba, which also has a point and is likewise single-bevelled, the Usuba is clearly very thin, so the tip is far less durable and is damaged much more easily than on a Deba or a Yanagiba.
As for small knives, Petty (petty) is an English-sounding name the Japanese coined themselves from the French petit. In English it is usually called a utility knife or a paring knife, because it tends to be used for odd jobs rather than for serious cooking. Its small blade makes it popular for cutting or peeling herbs and vegetables such as onions and garlic.