Yanagi-ba-bōchō (柳刃包丁, lit. willow blade knife), Yanagi ba or shortly Yanagi is a long and very thin knife used in the Japanese kitchen, belonging to the group of sashimi bōchō (Japanese: 刺身包丁, Sashimi [raw fish] bōchō [knife]) to prepare sashimi, sushi, sliced raw fish and seafood.
In preparing sashimi and sushi, there are very important conditions that the sliced cross section be smooth, shiny and sharp in a microscopic view. Those conditions cannot be met by other usual knives. Yanagi-ba-bocho is especially designed to satisfy the conditions. Important design points for it are as follows:
Length: It has a long blade to cut a fish block only in one direction (pulling). Zigzag cutting creates a bad cross section.
Thickness: It has a very thin blade to allow cutting using very little force. Using greater force would result in tearing or smashing instead of cutting.
Unstickiness: The back faces of some Japanese knives are scooped out to easily detach the sliced piece from the blade after cutting.
Hardness and toughness: Consistency in durability and sharpness is created in the same way as a Japanese sword. The blade is formed from a combination of two different steels, a softer outer jacket of steel (or wrought iron) wrapped around and forge welded to an inner core of harder, high carbon steel.
Single ground: A yanagi ba blade is angled only from one side, with the other side of the blade being flat. This allows control in the blade angle for delicate cutting and allows for ease of sharpening. The figures in this article are for right-handed version in which the blade is ground only on the right side (front face). Left-handed versions exist, but are relatively scarce and expensive.
Cutting direction: While almost all western knives are used to push and cut, almost all Japanese knives are used pull and cut instead.
The first two characteristics are particularly for yanagi-ba-bocho, and its name 'yanagi' is from long and pliant characteristics of a willow branch. The other characteristics are shared by all knives in Japanese cuisine. The important principle in using a yanagi ba to prepare sashimi is not cutting down but pulling with its long blade in a single motion.
