Katana - Aikido Knowledge Base - Aikido Glossary

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From Wikipedia, the free encyclopedia:

A Katana (刀 ?) is a type of Japanese sword (nihontō nihon=Japan to=sword), and is often called a "samurai sword." The term katana may be applied to the standard size moderately curved [as opposed to the older 'tachi" style featuring more curvature] Japanese sword with a blade length of greater than 60 cm (23.6 inches).[1] The term is sometimes incorrectly used as a generic name for any kind of Japanese sword.

The katana is characterized by its distinctive appearance: a curved, slender, single edged blade, circular or squared guard, and long grip to accommodate two hands. It has historically been associated with the samurai of feudal Japan, and has become renowned for its extraordinary sharpness and cutting ability, to the point that its purported cutting capabilities have reached mythical status.


Originally used as a general term for single-edged sword having "sori" or curvature of the blade. While the "sugata" or form can take many shapes, including double edged, characteristically the term is now used specifically to describe nihontō that are 26.5 inches and longer, also known as " dai" or "daito".

This distinguishes them from chokutō, which feature straight blades and were imported from China and Korea via trading. The chokuto is speculated to have been the first "sugata" type the katana took on, being modeled after the imported swords. This emergence of the first nihonto took place the same time period as the begining of Japanese fuedalism and recognition of daimyo or "the great family" in the late nineth century,

Pronounced kah-ta-nah, the kun'yomi (Japanese reading) of the kanji 刀, the word has been adopted as a loanword by the English language. As Japanese does not have separate plural and singular forms, both "katanas" and "katana" are considered acceptable forms in English.[citation needed]

Another term, Daikatana (usually given as the kanji 大刀), is a pseudo-Japanese term meaning "large sword". (In Japanese, 大刀 is actually read daitō. [2]) The reading mistake comes from the different ways Japanese Kanji can be read, depending on their combination or not in a word. It has been used in some (English-language) fictional works to represent a kind of large katana (perhaps better known as an ōtachi); the video game Daikatana, for example used this pseudo-term as its title. The correct name of this type of weapon is Tachi, and is different from ōtachi and Nodachi.


The katana originated in the Muromachi period (1392–1573) as a result of changing battle conditions requiring faster response times. The katana facilitated this by being worn with the blade facing up, which allowed the samurai to draw and cut their enemy in a single motion. Previously, the curved sword of the samurai was worn with the blade facing down. The ability to draw and cut in one motion also became increasingly useful in the daily life of the samurai.[3]

The length of the katana's blade varied considerably during the course of its history. In the late 14th and early 15th centuries, katana blades tended to be between 70 and 73 cm (27.6 and 28.7 inches) in length. During the early 16th century, average length was much closer to 60 cm (23.6 inches), but late in the 16th century, it was again approximately 73 cm (28.7 in).[3]

The katana was paired most often with the wakizashi or shōtō, a similarly made but shorter sword, both worn by the members of the warrior class. It could also be worn with the tantō, an even smaller similarly shaped dagger. The katana and wakizashi when paired with each other were called the daishō and they represented the social power and personal honour of the samurai.

Forging and construction

The legitimate Japanese sword is made from a specialised Japanese steel called "Tamahagane"[4]. The katana gets its gentle curve from quenching during forging, as it is straight prior to quenching. A process of differential tempering causes martensite to form predominantly in the edge of the blade rather than the back; as the spine has lower retained lattice strain, it cools and contracts, and the blade takes on a gently curved shape.[5]

What is used to harden a Japanese blade is a coating of clay mixed with ashes, as well as a small portion of rust, coating all but the edge. This gives heat insulation so that only the edge will be hard with quenching.

Hardening steel, through quenching from a heat above 1472 Fahrenheit (800 Celsius) (bright red glow), ideally no higher than yellow hot, at least within the common alloys of steel. If cooled slowly, it will break back down to iron and carbon. Though, if cooled quickly, it will stay as it is. The reason for the acquisition of the curve in a properly hardened Japanese blade is that iron carbide has a lesser density than its root materials have separately.


The katana's unique design and in particular its sharpness necessitate quite a few specialized precautions to handle it. Failure to observe these precautions can easily lead to damage to the weapon or severe injury.


See also: Battōjutsu, Iaidō, Iaijutsu, and Kenjutsu

Storage and maintenance

If mishandled in its storage or maintenance, the katana may become irreparably damaged. It is extremely important that the blade remain well-oiled and polished, as the natural moisture residue from the hands of the user will rapidly cause the blade to rust if not cleaned off. Similarly, when stored for longer periods, it is important that the katana be inspected frequently and aired out if necessary in order to prevent rust or mold from forming (mold may feed off the salts in the oil used to polish the katana).[6]

Ownership and trade in the United Kingdom

As of April 2008, the British government added swords with a curved blade of 50 cm (20 in) or over in length (and for the purposes of this sub-paragraph, the length of the blade shall be the straight line distance from the top of the handle to the tip of the blade) to the Offensive Weapons Order.[7] This ban was a response to reports that Samurai swords were used in more than 80 attacks and 4 killings over the 4 preceding years.[8] Those who violate the ban would be jailed up to six months and charged a fine of £5,000. Martial arts practitioners, historical re-enactors and people currently possessing such swords may still own them. The sword can also be legal provided it was made in Japan before 1954, or was made using traditional sword making methods. It is also legal to buy if it can be classed as a 'martial artist's weapon' [9]. This ban currently applies in England, Wales and Northern Ireland.

See also

* Tatara (furnace)
* Japanese swords

Similar Japanese swords

* Tachi/Nodachi/Ōdachi, often called by the pseudo-Japanese term daikatana and mistakenly labeled as a katana.
* Kodachi, often called by the pseudo-Japanese term chisakatana or kogatana and mistakenly labeled as a katana.
* Wakizashi, the short blade usually wear along with the katana.

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