The anatomy of a Japanese kitchen knife can be quite complex. There are many parts to a Japanese kitchen knife, and each has its own Japanese name. Very useful for those Japanese trivia nights, or for serious chefs who don't mess around. Interested in learning more? Scroll on!
A kitchen knife is an indispensable part of any kitchen and its anatomy is a symphony of form and function. Essentially, a knife consists of a blade, which is used for cutting, and a handle, which allows us to use the blade safely and comfortably. Understanding the different elements of the blade anatomy itself gives us an insight into the science, tradition and technology needed to produce knives for specific culinary tasks. Each part contributes to the overall efficiency and utility of the knife, making it a key food preparation tool in the hands of a skilled chef.
THE ANATOMY OF A JAPANESE BLADE
A Japanese kitchen knife is made up of many parts, each with its own Japanese name and specific purpose. Interestingly, the parts of the knife are named after parts of the body – each knife has a spine, and the blade curves in a belly and ends in a heel.
The blades also differ in the geometry of their cutting surfaces, which, together with the choice of steel, determine the perfect balance between sharpness and durability.
The cutting edge / hasaki:
For cutting, chopping and other cutting techniques, a sharpened cutting edge is used which runs the full length of the blade from heel to tip. This is the part of the blade that is the first to pierce through the ingredient, followed by the primary angle of the blade kireha. Having knowledge of the geometry and construction of the blade is crucial to understanding Japanese knives, we invite you to read more about this in our article on blade geometry, where we explain the grind angles and the composition of the cutting edge in more detail. For those who would like just a brief introduction to cutting edge geometry, here is a very brief summary: The term hasaki refers to the intersection between the inclined surfaces that form the cutting edge of a knife and determine the cutting ability of the blade. The term covers the geometry, angles and edge processing that contribute to the functionality of the knife.
Kireha is the primary angle of the blade, located between the cutting edge and the point of transition into the plane of the blade called the shonogi line. The kireha is the part of the blade that performs the cutting action and is carefully designed to ensure sharpness and precision. The grinding angle configurations of this part of the blade determine how the blade tapers towards the cutting edge, which affects its sharpness, durability and cutting performance. Based on the locations of the angle transitions between the planes, we can develop blade profiles into three types - convex, straight or concave.
The Japanese term for the hard core of a high carbon steel knife that forms the cutting edge of the blade.
Softer layer surrounding the core of the blade.
The line where the hagane and jigane converge. It runs in a sinuous line along the blade from heel to tip.
Shinogi is the distinct ridge or line where the hira breaks into the kireha, or, in other words, where the straight sides of the blade - the hira - and the primary edge of the blade - the kireha - meet. The shinogi is a structural and aesthetic element in the design of the blade. The break of the planes makes it possible to combine different blade finishes - for example, a kuro-uchi finish on the upper part of the blade and a kasumi finish on the lower part of the blade. If you are interested in learning more about blade finishes (damask, tsuchime, kasumi, etc.) on Japanese knives, we have an excellent article on this topic. There is no shinogi line in the convex geometry of the blade because there is a curve stretching from the spine of the knife to the hasaki.
Hira is the flat surface of the blade that extends from the shinogi line to the spine of the knife. The texture and shape of this part of the knife can determine to what extent food sticks to the blade. To minimize this, Japanese blades can have added hammer marks (tsuchime finish of the blade), which provide air pockets to reduce friction between the blade and the food. This flat part of the knife can be used for tasks such as crushing garlic, but be careful – the blade can become bent if the technique is not done correctly! Such tasks require great care and a gentle touch; the part of the blade used to crush the garlic must be carefully supported by the hand, and the handle must always be kept off the board.
The spine / mune:
The spine is the upper, uncut top edge of the blade where the handle continues into the blade. It gives stability and balance to the knife and is often used as a reference point in some cutting techniques. In forged Japanese knives, the spine gradually narrows towards the tip, which is called the distal taper - more about this is explained in our excellent article on blade geometry. The thickness of the spine can vary considerably depending on the type and shape of blade and its structure. Whether we are talking about a single bevel or a double bevel blade, the spine is usually thicker than the rest of the blade. Hand-forged knives with a distal taper, which have a thicker back, are more comfortable for the user, as the hand is better supported and the fingers are resting on a wider surface of the back when gripping. The geometry, rounded edges and finish details of the spine contribute to greater comfort during use and prevent blistering during intensive use of the knife.
Blade tip & point / kissaki:
The tip of the blade is the larger front part of the knife, which includes the knife point, and the knife point is the part of the knife where the cutting edge and the spine join. The blade tip and the point are used for fine and precise dicing of onions or shallots and for preparing meat. When using petty knives, the thin and precise tip is used for trimming and removing small pieces, such as the eyelets on potatoes. In the case of all knives, the point is also used for tenderising meat and cutting tendons. The knife point of the blade is also used for precision tasks such as boning chicken and filleting all small fish (regardless of knife type). The tip of the knife offers many uses, but it is imperative that one handles it gently.
The belly / sori:
The belly is the working surface of the knife. It is usually under more stress when rounded, which is generally the case in Western knives; the belly of traditional Japanese blades tends to be flatter. The roundness of the belly varies greatly depending on the type of blade and what its primary purpose is. Bunka, nakiri, and santoku tend to have a flatter belly, while gyuto has a slightly more curved one. The curvature of the cutting edge defines and allows the use of certain cutting techniques. In Japanese knives, a certain part of the cutting edge is always perfectly straight and gradually rises towards the blade point. The completely straight part of the blade is used to cut the wider bits of ingredients, and it also dictates the traditional cutting technique in Japanese cuisine – the 'push and pull cut', or cutting by pushing the blade forward and pulling it back. This technique is typically Japanese and differs from the basic Western rocking technique.
The heel / hamoto:
The heel is the widest part of the blade and closest to the handle. It is used for tasks that require more force. In certain cutting techniques, this part of the blade follows the movement of the belly and completes the cut. The heel is usually flatter than the rest of the blade and, in the case of blades with more curvature, can be used for quick cuts with a back-and-forth motion, such as cutting small vegetables into thin slices. There is a lot of variety in terms of function and thickness of the blade among different blade types – in the case of deba knives, this part is used to cut the bones of fish (here's a tip: in thicker bones, always look for softer spots such as joints and cartilaginous tissues). In santoku knives, however, the tip of the heel can be used to remove the eyelets on potatoes. The heel is traditionally used for peeling vegetables, but skilled chefs can use the heel to peel even the smallest foods, such as garlic, no matter their knife's size. In the case of yanagiba knives, when slicing raw fish for sashimi, the cut is made from the heel upwards, with the aim of using the entirety of the cutting edge. The tip of the heel can also be used to perforate the food (to soften meat and thicker vegetable pieces), which allows for faster heat penetration in the cooking process and reduces cooking time.
The choil / ago:
Machi is the lower part of the blade, positioned at the handle. In the region of Kanto, Japan, when attaching the handle, the machi is usually set a few millimetres away from the handle (the 'machi gap'), but in the region of Kansai the machi is set close to the handle.
Tang / nagako:
The tang is the part of the blade that is set into the handle. It is the extension of the spine of the blade, which is inserted into the handle. In Japanese knives, the tang is smaller and thinner than in the case of Western knives. This impacts the balance of the knife in Japanese handles and positions the centre of balance towards the tip of the knife, especially when combined with a light wooden handle. The different tangs are one of the crucial differences between a Japanese-type knife and a Western-type knife. You can read more on the differences between these two handle types and the tang anatomy below, or check out our in-depth article on the differences between Japanese and Western knife handles here.
THE ANATOMY OF A JAPANESE HANDLE
When choosing a quality knife, we can quickly notice the importance of the knife's balance and its feel in your hand. It is not only the blade that is important, the quality of the handle and its manufacture are equally important. When it comes to Japanese knives, there are two types of handle - the Japanese 'wa' handle and the Western 'yo' handle.
JAPANESE 'WA' HANDLES
The 'wa' handle is a characteristic feature of Japanese knives. It is a simple assembly of a wooden handle part (holder) and a collar (ferrule). Some 'wa' handles are made of just one piece of wood and do not have a ferrule.
The handle holder surrounds the steel tang of the blade. During handle fitting, the tang is heated and inserted into a piece of wood that shrinks at contact with the heated steel. Sometimes glue is added, too. The Japanese handle is usually made from natural wood (most often magnolia), and in some cases from composite materials (such as pakka wood) or stabilised wood. The handles vary in shape, the most basic and widespread shape being the oval, which is symmetrical in use and suitable for both left- and right-handed people. The octagonal shape is also symmetrical. This is followed by the D-shape, where the handle adapts to the guide hand. It is an unwritten rule that more expensive high-end knives have a symmetrical octagonal handle made of natural wood, a water buffalo horn ferrule, and various inserts made of brass or copper. In some exclusive lines they are silver, which has an additional bonus of antiseptic properties.
Collar (ferrule) / kakumaki:
Kakumaki is the ring at the top of a wooden Japanese handle, where the wooden part of the handle meets the blade. It has several important functions: It contributes to the functionality (by ensuring the structural integrity of the handle – it acts as a reinforcement that helps hold the handle together and increases the overall durability of the knife) and the aesthetics (it often has a contrasting colour to complement the handle). The material of the ferrule is most often plastic or made from water buffalo horn if the knife is more high-end. The ferrule also ensures a comfortable and secure grippable transition between the blade and the handle; together with the shape of the handle, it provides a smooth and ergonomic transition that allows a controlled grip when using the knife. In case of knives with wooden handles, the ferrule prevents the passing of moisture into the handle, which could otherwise cause swelling, deformation, or cracking. This protection increases the lifespan of the handle and the knife as a whole. A well-designed ferrule also contributes to an even distribution of weight between the blade and the handle, allowing for better control and manoeuvrability of the blade.
Butt / ejiri:
This is the end or bottom of the knife handle. In some extremely long yanagiba knives, the knife butt is additionally reinforced and works as a counterbalance to the heavy blade. This allows the centre of gravity between the blade and the handle to remain in the right place for efficient and comfortable use, despite the length and weight of the blade.
WESTERN 'YO' HANDLES
The 'yo' handle is a Western-style Japanese handle. Its typical feature is that the tang of the handle is encased in so-called scales, which are additionally attached to the tang by metal rivets. The tang may extend to the middle (partial tang) or to the end of the handle (full tang). The length and composition of the tang in Western-type knives affects the weight distribution of the knife and the final balance of the blade. The balance point of 'yo' handles is exactly at the contact point between the handle and the blade. If you like heavy and massive knives, the 'yo' handle is the right choice.
Yo handles are ergonomically shaped. The tang of the blade is sandwiched between two layers of material (also known as scales) and fastened with metal rivets. These scales are made of materials that are highly resistant to abrasion and are therefore appreciated in a professional working environment. They are usually made of plastic, laminated wood, stabilised wood, or (less commonly) natural wood, bone, or hornwood. Thanks to the use of modern composites, it is possible to recreate a myriad of colour combinations and shapes. For high-end knives, rare and more expensive materials are used, which have a strong visual impact on the overall image of the knife. Compared to 'wa' handles, they are extremely strong, which is why they are almost always used in certain heavy-duty types of blades, such as certain butcher knives, cleavers, honesuki blades, and boning knives. All these knives have a full tang construction with a 'yo' handle to give them the right balance, strength and wear resistance they need for heavy-duty jobs.
Yo handles may have a strong steel end (bolster) at the transition point from the blade to the handle. This is a thicker piece of steel that tapers from the handle to the heel of the knife. The bolster creates a smoother and more comfortable transition for the fingers to grip. The bolster is not necessarily an integral part of a Western handle, some do not have one. As a loose rule of thumb, knives with a bolster are slightly heavier.
Rivets are metal dowels that secure the handle material to the tang. Rivets can also have a decorative function, and many knives have mosaic rivets made of different materials.
Butt / ejiri:
The end or bottom of the handle of a knife. It is usually rounded, less often completely straight.
Handle pommel – decorative plate:
This is a finishing element on the bottom of the handle, which also has a decorative function. Some manufacturers add an engraving or a hand-carved kanji signature of the blacksmith's forge to the decorative plate. The handle pommel can be used in food preparation, too! It is recommended for tasks such as crushing garlic. In case of longer, larger, massive blades, the handle pommel is additionally reinforced on the handle and has the function of counterbalancing the heavy blade, thus - again - positively influencing the correct balance between the blade and handle.