Classification of Japanese Swords

Classification by Period

Japanese swords are categorized according to the period in which they were made:

Koto (古刀, “Old Swords”)
Refers to swords made from the late Heian period until the Bunroku era (1596). In terms of historical eras, this covers the Heian, Kamakura, Nanbokuchō, Muromachi, Sengoku, and up to the Bunroku era of the Azuchi-Momoyama period. (The Azuchi-Momoyama period marks a transitional stage from koto to shinto.)

Shinto (新刀, “New Swords”)
Refers to swords made from the Keichō era (1596) through the Meiwa era (1771). This corresponds to the time from Tokugawa Ieyasu, the first shōgun of the Edo shogunate, through the reign of the 10th shōgun, Tokugawa Ieharu (grandson of Yoshimune).

Shinshintō (新々刀, “New-New Swords”)
Refers to swords made during the turbulent times from the An’ei era (1772) of the Edo period up to the Meiji period. This spans from the later years of the 10th shōgun Ieharu to the reign of Emperor Meiji.

Gendaitō (現代刀, “Modern Swords”)
Refers to swords made from the Taishō era (1912–1926) onward.

Note: Swords made prior to the early Heian period are generally referred to as “jōkotō” (上古刀, ancient swords) and fall under the field of archaeology. However, the essential features of what we now call the Japanese sword had already been established during this early era. For details, see the section on the history of Japanese swords under Jōkotō.

Classification by Length

Japanese swords are also classified according to blade length (nagasa). (One shaku = approx. 30.3 cm)

• Katana (刀): 2 shaku or more
• Wakizashi (脇差): 1 shaku or more but less than 2 shaku
• Tantō (短刀): Less than 1 shaku

*Under the “Sword and Firearms Control Law” of Japan, blades 60 cm or longer are categorized as katana, those 30 cm or shorter as tantō, and those in between as wakizashi.

Tachi (太刀) vs. Katana (刀)

The distinction lies not merely in length but in how they are worn and used:

• Katana are worn thrust through the belt (obi) with the edge facing upward.
• Tachi are suspended from the belt with the edge facing downward.

Thus, they are differentiated by manner of wear and intended use, not simply by length.

Tachi were typically carried by high-ranking warriors on horseback, designed to strike down enemies on the ground. They were suspended edge-down so that the scabbard would not bump against the horse’s hindquarters.

Katana, on the other hand, developed as warfare shifted from mounted combat to ground-based duels where speed of draw was essential. The shallower curve of the katana allowed for quicker unsheathing, and being worn edge-up enabled the swordsman to cut as he drew.

Standard katana length was about 2 shaku 3 sun 5 bu (approx. 71 cm), while tachi were usually around 2 shaku 6 sun, and some from the Nanbokuchō period reached nearly 3 shaku. Many long tachi were later shortened (suriage) during the Azuchi-Momoyama period to make them more practical as katana. These shortened tachi, although originally forged as tachi, came to be registered and regarded as katana.

Kowakizashi (小脇差) & Sun-nobi Tantō (寸延び短刀)

These terms frequently appear in sword studies:

• Kowakizashi: A short wakizashi.
• Sun-nobi Tantō: A slightly longer-than-usual tantō.

It is important to note that classification depends on how the blade was originally made, not merely its length. For example, before the Muromachi period, wakizashi did not exist, so a blade measuring 1 shaku 1–2 sun would still be considered a long tantō (sun-nobi tantō).

Kodachi (小太刀)

Kodachi refers to short tachi, not wakizashi. While popular culture sometimes confuses “kodachi” with wakizashi or uses the term for women’s swordsmanship styles in fiction, in the context of Japanese swords, kodachi are properly considered short tachi.

An example is a kodachi by the Kamakura-period Yamashiro smith Nijikunitoshi, designated an Important Art Object. Though its length would place it in the wakizashi category under modern classification, it is in fact a tachi.

Other kodachi, such as those by Rai Kunitoshi, were ceremonial swords (gijō no tachi) used in aristocratic rites, often with distinctive nakago (tang) shapes like the kijimomo-gata (“pheasant thigh form”). These were sometimes made for the coming-of-age ceremonies of imperial or noble children.

Koshigatana (腰刀) & Uchigatana (打刀)

• Koshigatana: A general term for short swords without guards (tsuba), worn thrust into the belt. They ranged from tantō-length to katana-length. They were used for self-defense when removing armor or in close combat after arrows were spent.
• Uchigatana: Used by retainers and warrior monks who could not ride horses. Unlike piercing weapons, these were cutting swords, hence the name “uchigatana” (literally “strike-sword”). Early examples were about the length of a modern wakizashi.

Over time, longer koshigatana and uchigatana, both worn edge-up through the belt, developed into what we now recognize as the katana. It is said that the katana emerged both from the evolution of koshigatana used by higher-ranking samurai and from uchigatana used by lower-ranking warriors.