12 Signature Zukuri (Blade Shapes) in Japanese Swords
Zukuri refers to the construction or the blade’s shape of a Japanese sword. This blade design can come in various styles that can completely change the function of a sword. They can differ in terms of their cross-sectional profile, ridge-line, curvature, width, thickness, and the general form of the blade.
Many types of zukuri forms frequent on Japanese swords can differ based on how the bladesmith forms them in the hizukuri process. Broadly, zukuri types can be classified into those designed for longer and shorter swords, with some forms bridging the two categories.
In this article, we will look at the many different zukuri types and explain their characteristics. We will group them into two categories based on the popularity of their use on longer or shorter swords. We will examine the most popular styles, such as the shinogi–zukuri, most frequently used on katanas, to the less known zukuri profiles, such as the hocho–zukuri, used on shorter tanto daggers.
Longer swords such as the katana, tachi, naginata, nagamaki, and wakizashi feature different blade zukuri designs, making them different in their cutting, thrusting, and handling attributes.
The shinogi–zukuri is a Japanese sword with a blade with a shinogi or a ridge line running along its entire length where the blade is thickest. This style is the most used on Japanese longer swords such as the katana, tachi, and wakizashi and is standard for many Japanese swords on the market today.
This zukuri style is also one of the oldest and most frequent on Japanese authentic or replica swords. It has a bend or curve to make drawing the blade out of its scabbard easier, and the ridge line was higher than previous Japanese swords. The ridge line can be slightly closer to the spine and usually has a well-defined yokote point.
Opposite the previously mentioned shinogi–zukuri is the hira–zukuri, which has flat blades on both sides without a shinogi ridge line running across its center. It also lacks a yokote or a well-defined area that separates the blade from its sharp tapering tip.
The hira–zukuri is simple in design, and although more frequent on longer swords such as the katana and wakizashi, it can also be popular on smaller dagger tanto blades. The flat-sided blades can serve as a base and be combined with other zukuri styles, which can be broader at the spine, feature a cross-section like a triangle in the center, or have another zukuri shape on the other side of the blade.
The myth is that the hira–zukuri isn’t as powerful as other zukuri types due to the lack of a shinogi ridge line. Various bladesmiths have debunked this multiple times, including Walter Sorrells, a specialized bladesmith focused on making authentic Japanese swords.
This is the oldest style of a Japanese zukuri shape that was frequent on Japanese single-edged swords known as chokuto or jokoto, which took inspiration from Chinese blades. The blade is straight in design, with a shinogi ridge line running very close to the cutting edge. There can be a defined yokote and a koshinogi, the line touching the spine at the tip, but the kissaki blade tip is narrow and small.
This style would be replaced with a shinogi line running much higher on the blade surface so the bevel can be longer and better sharpened. This zukuri style would be used alongside the other later zukuri styles, but mostly on ceremonial blades.
The katakiriha–zukuri looks unorthodox because it has two different types of zukuri blades. One side of the blade can be flat and feature a hira–zukuri style of blade shape, while the other can have a shinogi ridgeline running throughout its entire length.
Depending on the other zukuri shape and the design of the ridgeline, it can be a katakiriha–zukuri combined with a hira–zukuri and shinogi–zukuri, shobu–zukuri, or even an early curved type of a kiriha–zukuri. These shapes emerged in the Kamakura period (1185-1333) as experiments for blades to deal with different types of armor, especially with the arrival of the Mongols in the late 13th century.
The shobu–zukuri blade shape has a ridge line running across its entire length from the guard until the tip, without the presence or marking of the yokote and kissaki tip point. It is similar to the shinogi–zukuri but has no well-defined point that splits the blade part from its kissaki zone.
This type of zukuri was mostly developed and used in the many battles of the Muromachi period (1336-1537). This style was introduced to many different sword types, such as the tachi and katana, but was mostly used on the wakizashi and tanto.
The nagamaki–zukuri is similar to a shinogi–zukuri blade shape with a ridgeline running across its center. However, it features a large groove starting just above the blade tang underneath the handle. The central ridge line has a strong bevel toward the blade’s unsharpened spine in front of this groove.
This groove, or fuller, is often accompanied by a smaller groove that runs below the central one. These fullers help to lighten the sword’s weight and make it more flexible. It can be frequent on katana blades and nagamaki swords, which were heavier, larger, and used with sweeping attack motions to deal with armor and enemy cavalry.
The kissaki–moroha–zukuri, better known as kogarasu–zukuri, is a type of Japanese blade shape that would make a single-edged blade with a double-edged tip. It first appeared during the Nara period (710-794) in Japan, and some see it as the bladesmith’s experiments with earlier double-edged blade profiles mixed with the newer single-edged ones.
It has nagamaki style zukuri with bevels and grooves, and the spine broadens in a flat portion, almost 1/3 of the distance near the tip.
This style of zukuri is more popularly called kogarasu–maru style, a nickname translating to Little Crow for an antique sword with the same style of zukuri. It belonged to the 12th-century Taira family and is in the imperial swords collection today. It is believed that it was constructed by the legendary bladesmith Amakuni, who was believed to be the creator of the first single-edged Japanese sword.
The zukuri designs seen on shorter swords were mostly made for a more rigid structure or for taking away the weight of the blade for easier handling. Some of these blade types were used on larger blades, too, but they were more frequent on shorter swords such as the tanto and wakizashi.
The moroha–zukuri has a sharp edge on both sides of the blade while featuring an asymmetric form for the ridge line. They are usually straight in design, such as the Ken double-edged sword, or some later moroha–zukuri types can feature a slight curve toward their tips. This blade style can have a well defined ridge-line that crosses through the whole of its blade length.
It was a zukuri style used on the smallest Japanese swords, such as the tanto, but it was fairly uncommon.
The kanmuriotoshi–zukuri was also a fairly unorthodox and complex blade profile. It had a single-edged blade, its spine becoming thicker and much wider from the center to its tip point. It did not feature a yokote line to define the kissaki and had a ridge line across the tip that extended from the guard until the very tip. Some could feature a type of fuller design before this thickening of the blade, too.
These blades were also straight in design and made with a rigid structure for more powerful stabs with shorter swords like the tanto. It wasn’t a popular design, and it was mostly made by yamato sword schools dating back to the Kamakura period (1185- 1333).
Unokubi–zukuri styles were used on shorter as well as larger swords. They had a very similar design to that of the kanmuriotoshi–zukuri, with the presence of a yokote-defining line near the tip. At roughly 1/3 of the blade’s tip, there is a type of fuller, which is a part of the blade taken out to lighten the weight and make the sharp tip wider for slashing. The weight gets redistributed back toward the hilt, which makes the sword easier to handle.
This zukuri style was popular on naginata blades and even katana swords, but it could also be seen on various tanto daggers. Unlike the kanmuriotoshi–zukuri, the unokubi blades were mostly curved.
The osoraku–zukuri blade profile was popular on shorter blades because its design could not function well on larger blades. It had a thin first half of the blade, while it extended and became much wider near the kissaki tip point, making the second half bigger than the first. It could feature a ridge line running through the entire blade length marked with a yokote somewhere near the blade’s center.
This fairly complex blade style could be utilized for powerful stabbing and thrusting attacks that might open bigger wounds. It is believed to have originated from Shimada Sukemune, who made many different styles of swords during the 15th century.
The hocho-zukuri is one of the simplest forms of a blade profile frequent on Japanese tanto swords. They are flat on both sides without a ridge line or fuller going across it. The blade is usually broader in design than any other type of tanto sword.
Its full tang is also wider, making its handle a bit broader and making these tanto swords seem short and thick in design.