I've been making sushi for a while at home and now decided to get a set of knives specifically for this purpose (as I have only a couple of general-purpose knives which are horrendous).
The question is - which types of knives should I get? Is there a one universal knife for cutting rolls & carving fish & making sashimi or there are several and what are their names? Maybe there is a standard set for this?
The traditional knife for sushi and sashimi is the yanagi sashimi. It features a long blade (approx 10in or 270mm) that has a chisel ground blade which is often hollow ground on the back, called urasaki. The long blade allows you to cut thin slices in one continuous motion so that you don't you don't have slashes marks from changing direction. There are also other traditional Japanese knives for specific food preparation tasks such as vegetable chopping and meat preparation. If you already have European-style knives you are comfortable with, there is no need to purchase Japanese-style knives for those tasks.
I would suggest getting a single, long sujihiki style knife with the following features:
High-carbon stainless or carbon steel - This will help maintain a sharp edge with good retention. Carbon steel needs to be kept very dry to avoid rusting, so it's a little harder to maintain.
Comfortable grip - Cutting sushi involves long, repeated and consistent slices and fish is slippery to work with so you will need a grip that will not slip in your hands and affords very strong precision not only on the pull part of the cut but also in blade positioning.
Shallow height - Raw fish creates a lot of friction on a blade, which is why sushi knives are low-profile in height. This reduces surface area in contact with the fish, which in turn reduces friction.
Moderate thickness - Professional sushi knives are actually quite thick, because they are designed to allow the fish to peel away from the edge, to reduce friction. However, sushi chef's are trained to be able to use these blades without having the knife drift while cutting...home chefs are rarely able to master this movement so I would not get a knife that is too thick.
Rigidity - A good sushi knife is long but rigid. You want the cut to be clean and straight so the knife cannot flex while you're cutting.
Bevel geometry - If you're ambitious, go ahead and get a single bevel sushi knife. This will be a lot sharper, but much harder to maintain.
Professional sushi knives are actually not necessarily hard. Sushi chef's know how to sharpen their knives with wetstones and hones, so they often prefer to work with slightly softer steel because it's easier to maintain. I wouldn't recommend this approach at home because it's hard to get sharpening done at the appropriate angles, so it's usually a better tradeoff to go with a high performance, hard steel like VG-10, japanese blue steel or CPM154 which will hold an edge pretty well without need for frequent sharpening.
