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Japanese swords have been shaped by Japan’s climate and history. However, each sword type differs according to era, region, school, atelier and individual swordsmith. As such, it is difficult to pinpoint some unique characteristics shared by all Japanese swords. If we were to try, though, perhaps we could distinguish three common components: the use of iron (and not just tamahagane*); the shinogi-zukuri (ridged) construction*; and the use of orikaeshi tanren (repeated folding and forging)*.

Iron swords first appeared in Japan in the Yayoi period (ca. 5th century BC–3rd century AD). The first specimens were straight swords brought over from mainland China. Swords were first produced in Japan during the Kofun period (ca. 3rd century–ca. 7th century). Iron swords were placed in the tombs of powerful figures, so many examples have survived to the present day. These swords have extremely short nakago (tangs)*, which suggests they were held in one hand when fighting.

Tangs became longer from the middle of the Heian period (794–1192) to enable swords to be held in two hands. Blades also became curved, with this marking the emergence of the shape we now associate with Japanese swords. It seems sword handling techniques also changed significantly during this time. Each subsequent era also saw its own refinements and improvements, with each region producing master swordsmiths with their own distinctive styles.

When it comes to lethality, Japanese swords have not evolved substantially from the straight swords used during the Kofun period. Distance meant that bows were the first weapons to be employed on actual battle grounds. Bows were later replaced by guns and other firearms. As the distance between enemies gradually closed, spears were the next weapons to be employed. During this period, swords stood no chance against these longer-range bows, firearms and spears. Military generals only drew their swords as a very last resort. Swords were used for protection in that final phase when the enemy was close enough for hand-to-hand combat.

Nonetheless, Japanese swords still feature prominently in many captivating tales and legends, where they are wielded by historically-famous generals, eulogized for cutting down demons and evil spirits, or forged with the help of deities. For Japanese people, swords were imbued with a sacred power that raised them above mere weapons, with this elevated status epitomized by Kusanagi-no-Tsurugi, one of the three sacred treasures inherited by emperors from generation to generation. In the Muromachi period (1392–1573), swords became objects of aesthetic appreciation and they also served as valuable gifts in the samurai society that prevailed from medieval times, with one family (the Hon’ami) even establishing itself as an independent sword appraiser. Based on this, we could even say that the true worth of Japanese swords lies in their aesthetic and symbolic values.

For the layperson, though, sword appreciation is no simple matter, with the swords lined up in museums seemingly indistinguishable from one another. When appreciating swords, the first thing to focus on is the hamon, a white pattern along a blade’s cutting edge that emerges through tempering. Japanese swords are forged through a process of differential hardening, whereby clay of varying thickness is applied to the blade and the cutting edge heated, with the sword then rapidly cooled using water. By adjusting the thickness of the clay and the timing of the quenching, sword makers can create a sword with both a hard cutting edge (making it very sharp) and a flexible-yet-tough spine and inner section (making it difficult to break). The white pattern that then emerges through polishing is called the hamon. From the middle of the Kamakura period (1192–1333), swordsmiths became aware that the way clay was applied gave rise to different hamon. This led sword makers and schools to create their own distinctive hamon patterns. As the ground metal used in swords became more standardized from the Edo period (1603–1868), hamon became even more important forms of expression, with some even featuring pictorial representations of Mount Fuji or cherry blossoms, for example.
To conclude, here is a list of museums with permanent sword displays. If you are interested, please visit one of these to witness the beauty of swords for yourself.

・The Japanese Gallery (Honkan), Tokyo National Museum (Tokyo)　check it for more details
・The Japanese Sword Museum (Tokyo)　official website
・The Gallery 1F-5 (Metalwork), Heisei Chishinkan Wing, Kyoto National Museum (Kyoto)　check it for more details
For the purpose of preserving the artworks, the Heisei Chishinkan Wing regularly rotates its exhibits. Please note that swords may not always be on display. Before your visit, we recommend checking the Kyoto National Museum website for the latest exhibition schedule.

Tamahagane

Tamahagane is a type of steel used in Japanese swords. It is an iron and carbon compound. Japan’s Firearm and Sword Possession Control Law stipulates that authentic Japanese swords must contain tamahagane. The steel’s production dates back to around the 6th century. It is made by reducing iron sand and iron ore in a hot furnace supplied constantly with air using bellows. The technique was refined over time and reached perfection with tatara ironmaking, a process that utilizes a tatara furnace operated with a foot-operated bellow. The name “tamahagane” is relatively new and actually derives from a trade name used from the end of the Meiji era (1868–1912) to the start of the Taishō era (1912–1926).

Shinogi-zukuri

This style is seen in tachi long swords, uchigatana mounting, and wakizashi short swords, for example. It features a high ridge line running along the sword between the cutting edge and spine (the non-cutting side), with this three-dimensional construction imbuing the entire sword with strength and toughness.

Orikaeshi tanren (repeated folding and forging)

This process removes impurities from the steel while adjusting the carbon content. The tamahagane steel is heated until the surface starts to melt. It is then folded and hammered out, with this process repeated around 12 to 15 times.

Nakago (the tang)

This is the part of the sword that fits in the hilt. It is filed down without any polishing. The swordsmith’s name or the production date is sometimes inscribed on the tang.

Tachi (long sword)

Tachi are curved swords with a shinogi-zukuri (ridged) style. Their hilts are designed for two-handed handling, with the swords hung from the waist. It is believed tachi first emerged during the late Heian period (794–1192).