Japanese sword

Japanese: 日本刀 - にほんとう

Japanese swords are a general term for Japanese swords, including tachi (long sword), katana (katana), wakizashi (short sword), and tanto (short sword), but in a broader sense, they also include all swords made by swordsmiths, such as naginata (long sword), and spears (yari). Unlike Western swords, Japanese swords usually have long handles, are used with both hands, have a curved single-edged blade, and long ones are shinogi-zukuri (ridged). They are made using a unique forging method that wraps soft iron around the core and steel around the skin, and many of them are excellent in functionality and sculptural symmetry. Furthermore, as a result of hardening only on the blade and not the entire blade, the hamon (blade pattern) appears, and together with the pattern of the raw surface (grain) created by forging the steel, they express a unique beauty.

[Nobuo Ogasawara]

The History of Japanese Swords

The history of Japanese swords dates back to the Kofun period, but since then, they have changed due to many historical factors, including political systems, fighting methods, economic structures, production techniques, craftsmanship systems, customs, and habits.

[Nobuo Ogasawara]

Ancient

The earliest forms of Japanese swords were those imported from the continent, or were modeled after these, and were straight swords with a single handle. A distinctive feature of the development of swords in Japan is that there is little difference in time between bronze implements such as bronze swords, bronze spears, and bronze halberds, and iron implements. Bronze swords and other implements were introduced to the Kitakyushu region at the end of the early Yayoi period around the 2nd century BC, but iron swords, iron halberds, and plain ring-headed large swords appeared as early as the late Yayoi period in the 2nd to 3rd centuries AD (note that the ancient straight sword is written as large sword, and the later curved sword (curved sword) is written as tachi to distinguish it).

As the Kofun period began at the end of the 3rd century, iron weapons became mainstream, but long swords up until the 5th and 6th centuries were single-edged straight swords in the Hirazukuri style (single-edged construction with no ridges). A representative example is the silver inlaid long sword (national treasure) excavated from the Etafunayama Kofun in Nagomi-cho, Tamana-gun, Kumamoto Prefecture. The sword fittings have gilt bronze plates attached to the surface of the wooden handle and sheath, on which carvings and hammered-in patterns such as dragons, arabesques, circles, and warabi-de patterns can be seen. The pommel of the early days was a plain ring, but eventually came to be decorated with various designs such as a single dragon, double dragons, a lion's bite, and trefoil, and in addition to the ring head, other shapes included a round head, square head, keiko head, bird's neck, and kabutsuchi.

Around the 7th century, the style shifted from Hirazukuri to Kiriha-zukuri (a style in which the ridgeline is closer to the blade), but this is thought to be a new style created during the Sui and Tang dynasties in China. The Heishi Shorin Sword and Shichisei Sword (both national treasures), said to have been worn by Prince Shotoku and kept at Shitennoji Temple in Osaka, are representative examples of Kiriha-zukuri large swords imported from the continent. There are almost no straight swords to be found, but the Shosoin Treasures contain 55 large swords, 5 teboko, 33 hoko, and 70 tosu, and the large swords are basically made in three types: Hirazukuri, Kiriha-zukuri, and Kissakimoroha-zukuri (a style in which only the tip is double-edged). If we interpret literally the names of the Chinese-style swords, which are listed in the catalog of these items, "Todaiji Temple Offerings Book" (also known as "National Treasure Book"), and distinguish them from the Chinese-style swords, the former would be made on the continent, and the latter would be imitations made in Japan. Among the sword fittings, the gold and silver inlaid swords, which use skilled techniques of lacquer and engraving, are outstanding.

[Nobuo Ogasawara]

Heian Period

The transition period from straight swords to curved swords is unclear, but judging from existing swords, it is thought to have been after the mid-Heian period. That is, the black lacquered sword in the possession of Kurama-dera Temple, which is said to have been worn by Sakanoue no Tamuramaro, is a straight sword with a cut blade, but the Nishikizutsumikenuki-style sword from Ise Shrine, which is said to have been worn by Fujiwara no Hidesato (Tawara Tōta), has a strong curve in the hilt and a construction where the ridge of the ridge is almost in the center, which is understood to be a transitional piece until the Japanese sword style (a curved sword with a ridge) was completed. The time when the Japanese sword was perfected coincided with the time when the land allotment system of the Ritsuryo society collapsed and the manor system developed, resulting in the birth and growth of a new samurai class, and also with the time when the armor changed from tanko (short armor that only covered the torso) and keiko (shoulder armor) to the perfection of o-yoroi (large armor). The curved Japanese sword style has the advantage of being less impactful than a straight sword when cutting something, but it is not an easy technique to make the thin side of the blade of the sword bend toward the thick side of the ridge and then temper the blade. Therefore, the appearance of the curved sword is thought to be due not only to the necessity of slashing from horseback, but also to the production of high-quality iron materials and the progress of forging techniques. Furthermore, the wearing of heijo (battle swords) was prohibited in the Kinai region of Kyoto in 983 (Eikan 1) and 987 (Eien 1), which suggests that a considerable number of swords were in general circulation at the time.

In the style of tachi swords from the Heian period, the width of the blade is narrowed by about half at the tip compared to the base, the tip is small, and the curvature is strong at the waist and almost non-curved at the tip. The nakago (the part that fits into the handle) is tapered and curved, and some are pheasant-legged due to the way the sword is fitted. In terms of the blade pattern, while the straight blades of the previous era were simple and weak, with uneven boiling and irregular edges, the blades were technically immature, but the famous swords of this era, while still having a straight blade style, have fine changes to the small irregularities, such as intersecting feet and leaves, and kinsuji (a beautiful pattern of shining lines formed by boiling that connects in the blade), clearly demonstrating the improvement in technique. In the late Heian period, many swordsmiths emerged from all over the country, some of the most prominent being:

● Sanjo Munechika He lived in Sanjo, Kyoto around the time of Eien (987-989), and is therefore known as Sanjo Kokaji. Kokaji refers to those who make products from iron, and those who work in ironworking are called o-kaji. His family included Yoshiie, Kanenaga, Kuninaga, Arinari, and Chikamura.

● Kobizen Tomonari and Masatsune Bizen Province (Okayama Prefecture) has long been the largest sword-making region, due to the production of iron from the Chugoku Mountains. These two are said to have been around the Eien or Joho eras (1074-77), but several craftsmen of the same name are thought to have existed until the Kamakura period. In the Kamakura period, the Ichimonji school arose in Bizen, founded by Norimune, but Bizen items made before that are collectively called "Kobizen."

●Hoki Yasutsuna On the opposite side of the Chugoku Mountains from Bizen, Hoki Province (Tottori Prefecture) also produces a lot of iron, and Yasutsuna is famous as a master craftsman. One theory is that it was around the Daido period (806-810), but the Nagano theory is correct.

●Miike Mitsuyo Tenta Mitsuyo of Miike in Chikugo Province (Fukuoka Prefecture) is said to have lived around the time of the Joho era, and is one of the most representative blacksmiths in Kyushu, along with Choen of Buzen Province (Fukuoka and Oita Prefectures), Joshu of Bungo Province (Oita Prefecture), and Yukiyasu of Satsuma Province (Kagoshima Prefecture).

[Nobuo Ogasawara]

Kamakura period

The Kamakura period (1192-1333) was a period of great development for swords, lasting for about 150 years. Looking at the process of change, the period can be roughly divided into three periods of 50 years each. In the first 50 years, the mainstream was still elegant swords inheriting the style of the Heian period, but it is important to note that among them, large and magnificent swords appeared. The Kamakura period was a time of intense conflict between temples and shrines and the power of the nobility against the power of the samurai. In sword history, blacksmiths who were enslaved to temples played a major role, but of particular note were the blacksmiths who served the Emperor Gotoba on a monthly rotation. The retired emperor summoned master swordsmiths from the Awataguchi school in Kyoto and from Bizen and Bitchu, set monthly shifts to forge swords, and personally hardened the blades.

In the mid-Kamakura period, tachi swords were broad, flat, not too narrow at the tip, and sturdy with a layered shape. The tip was also narrow at the middle and had a sharp neck, showing its grandeur. The flamboyant hamon style of clove-shaped blades was born in Yamashiro (Kyoto Prefecture) and Bizen, but many of the styles were inspired by Yamato blacksmiths. This is thought to be because swords from Yamashiro and Bizen were sold, while Yamato blacksmiths were subordinate to temples and shrines and followed traditions. Tanto swords (the term did not come into use until the early modern period, and were called koshigatana or chiisagatana in the past) were practical consumables, so there were few surviving examples from the early period and nothing particularly noteworthy, but by this time there were many masterpieces. Most of them are ordinary, flat-built and curved inwards, with either straight tangs or ones with a large curve on the ridge, known as furisode tangs. Naginata have been seen in picture scrolls and other works from the previous period, but those from the mid-Kamakura period all have little curvature and do not bulge. Spears are rarely seen. Swords are the same size as tanto, but they were used as ritual implements in esoteric Buddhism rather than as weapons.

Following two Mongol invasions in 1274 (Bun'ei 11) and 1281 (Kōan 4), the shogunate worked to build up its military strength by defending the Kyushu coast. These Mongol invasions had a major impact on the tactics and weapons of Japan, and swords from the end of the Kamakura period were emphasized as being more grandiose, while the flamboyant blade patterns of Yamashiro and Bizen swords were less common. Meanwhile, in Kamakura, the shogunate's base in Sagami (Kanagawa Prefecture), the Sagami tradition was perfected by Shintō Gokunimitō and his disciple Masamune. This style combines hard and soft jigane (metal steel) to express the beauty of the boiling pattern created by the large blade patterns based on chikei and kinsuji (gold lines) and wavy blades. Masamune's style in particular had an impact nationwide, and has remained a classic example of Japanese sword beauty for generations to come.

The following are noteworthy lineages of swordsmiths active during the Kamakura period, which is generally considered the highlight of the history of swords in Japan.

●Yamashiro Blacksmiths After the Sanjo school, the Awataguchi school emerged in Kyoto, and included the six brothers Kunitomo, Hisakuni, Kuniyasu, Kunikiyo, Arikuni, and Kunitsuna, and later Kuniyoshi and Yoshimitsu. In the later period, the Rai school, including Kuniyuki, Kunitoshi, Kunimitsu, and Kunitsugu, flourished in place of the Awataguchi school, but Ayano Koji Sadatsugu and Ryōkai were also famous.

● Bizen Blacksmiths The Ichimonji school has produced many master craftsmen, known for their gorgeous clove-edged blades, and representative craftsmen include Yoshifusa, Sukezane, and Norifusa. From the middle of the period, the Osafune school flourished, beginning with Mitsutada, followed by Nagamitsu, Kagemitsu, and Kanemitsu, and blacksmiths of this school date from the Muromachi period to the end of the Edo period.

●Yamato Blacksmiths Five schools are famous: Senjuin, Taima, Tegai, Hosho, and Shikake. Senjuin, Tegai, and Shikake are blacksmiths from Nara, while Taima and Hosho are blacksmiths from southern Yamato, and all of them have close ties to temples.

●Sagami blacksmiths It is said that Kunimune and Sukezane came to Sagami from Bizen, and Kunitsuna from Yamashiro, but it is not clear. In fact, it began with Shintogo Kunimitsu, and the style was perfected by his disciples Yukimitsu, Masamune, and Norishige.

[Nobuo Ogasawara]

The Northern and Southern Courts Period

Although this period only lasted about 60 years, it was a time of great change in the history of swords, when the boldness and sturdiness of swords were exaggerated to the maximum. Some swords, called no-tachi and seoi-tachi, were more than 3 shaku (about 91 cm) wide, but many of these were later polished and turned into uchigatana (swords worn at the waist for combat), and as a result, those with the raw tang (the tang as it was when forged) are rare, and many are unsigned due to extensive polishing. Apart from the o-dachi, smaller tachi also appeared in the late Northern and Southern Courts, and from this time uchigatana began to grow to the same size as tachi and became popular, and tanto also became wider and curved, becoming larger, exceeding 1 shaku. This trend created an ideal stage for swordsmiths in various regions, as will be described below, and the Southern and Northern Court era names inscribed on swords from this period also serve as a source of information about the imperial court's rule in each region.

● Sagami blacksmiths After Masamune there was Sadamune, then Hiromitsu and Akihiro, who all display the distinctive Hitatsura blade style.

The Yamashiro blacksmiths were replaced by the Nobukuni blacksmiths, who had a strong workshop-like character, and several of the same name continued into the Muromachi period. The Hasebe school is famous for Kunishige and Kuninobu, and their style of knives is similar to that of the Sagami school.

●Mino Blacksmithing This school flourished greatly after the Northern and Southern Courts period and is said to have been founded by Kaneuji Kaneuji of the Yamato Tegai school, who moved to Shizu in Mino (Gifu Prefecture) and called himself Kaneuji, and studied under Masamune. A disciple of the school then moved to Naoe (Yoro Town) and founded Naoe Shizu. Kaneshige also moved from Tsuruga in Echizen (Fukui Prefecture) to Seki, and became the founder of Seki blacksmithing.

●Bizen blacksmiths The Osafune school, headed by Kanemitsu, seems to have split into several branches, including Chogi, who inscribed his swords with the era names of the Southern Court, Morikage of the Omiya school, and Tomomitsu, Hidemitsu, and Masamitsu of the Kozori school, but Nagagi's style is superior.

●Bicchu Blacksmiths There were Aoe blacksmiths in Bitchu (Okayama Prefecture) from the early Kamakura period, and the Aoe products of this period were called Sue Aoe, and Tsuguyoshi and Tsugunao showed their skills in straight blades and reverse clove swords.

Other notable schools include the Samonji school in Chikuzen (Fukuoka prefecture) and the Enju school in Higo (Kumamoto prefecture).

[Nobuo Ogasawara]

Muromachi period

With the unification of the Northern and Southern Courts in 1392 (Meitoku 3), the Muromachi period began, and the Ōdachi swords of the Northern and Southern Courts period fell out of fashion, and tachi swords closer to the Kamakura period style appeared. On the other hand, the tachi swords, which had been worn by lower-ranking samurai since the previous period, gradually became more popular and replaced the tachi as the mainstream of swords. This is the same phenomenon as when armor (dōmaru and haramaki) worn by low-ranking foot soldiers and soldiers became more luxurious and was worn by even higher-ranking samurai. Spears also became increasingly popular, and became a major weapon along with bows and arrows. In this environment, many wakizashi swords with ridged edges measuring 1 shaku 3 sun (about 40 cm) to 1 shaku 7 to 1 shaku 7 or 8 sun were produced. These were probably tachi swords that were attached to tachi swords, but in the later period they became about 2 shaku long and had a strong curved tip, which was a style that well reflected the characteristics of the era. However, on the other hand, reflecting the frequent occurrence of wars, there were also many inferior swords produced, known as kazuuchimono or tabagatana.

The introduction of firearms in 1543 (Tenbun 12) transformed not only swords and armor, but also castles, tactics, and even social structure, but these changes also produced a large number of swordsmiths, such as those in Uda, Ecchu (Toyama Prefecture), Fujishima, Kaga (Ishikawa Prefecture), Shimada, Suruga (Shizuoka Prefecture), Sengo, Ise (Mie Prefecture), Shimohara, Bushu (Saitama Prefecture), Kaifu, Awa (Tokushima Prefecture), and Takada, Bungo (Oita Prefecture). The following two schools were particularly prominent:

Mino Blacksmiths In the east, the largest sword-making area during the Muromachi period was Seki in Mino, which is thought to be because there was a samurai troupe based in Kasuga Shrine. All Mino blacksmiths have the character "Kane" in their names, and famous ones include Izuminokami Kanesada, Kanefusa, Kanemoto, and Kanetsune. Another distinctive feature of Seki blacksmiths is that they would migrate to various places to forge swords.

Bizen blacksmiths from the Oei period (1394-1428) are called Oei Bizen, and the well-known names are Morimitsu and Yasumitsu. Bizen blacksmiths from the end of the Muromachi period are called Setsu Bizen, and representative craftsmen include Katsumitsu, Munemitsu, Yozaemon-no-jo Sukesada, and Magoemon-no-jo Kiyomitsu.

[Nobuo Ogasawara]

Momoyama period

In the world of swords, swords made before the Keicho era (1596-1615) are generally called Kotou and swords made after that are called Shinto. This is because Toyotomi Hideyoshi's sword hunt resulted in the elimination of inferior swords, known as Kazuuchimono and Tsukasa swords, which had been mass-produced up until that point, and led to the creation of swords with a completely different style. Some of these swords were modeled after famous swords from the Kamakura and Nanboku-cho periods, and swordsmiths began to settle in the newly established castle towns of feudal lords. Famous swordsmiths from the Keicho to Genna periods (1615-24) include Horikawa Kunihiro, Masahiro, Kunimichi, and Umeda Myoju from Kyoto, Kanedo, Yoshimichi, and Masatoshi from the Sanpin school, Tadayoshi and his school from Hizen (Saga Prefecture), Shigekuni from Nanki, Yasutsugu from Echizen, and Shigeyoshi from Edo. During this period, large tachi swords from the Kamakura and Nanboku-cho periods were polished and remodeled into uchigatana swords, and newly produced swords were similar in appearance to these swords, with a wide blade, long tips, and shallow curvature. Masamune and Sadamune from Sagami Province in particular were considered ideal.

[Nobuo Ogasawara]

Edo period

The period from the Kan'ei era (1624-1644) to the Genroku era (1688-1704) was the heyday of the samurai class, and the period when new swords were in vogue. Swordsmiths were active mainly in Edo and Osaka, and in Edo, Nagasone Kotetsu, Hojoji Masahiro, Yamato no Kami Yasusada, Kazusa no Suke Kaneshige, and Ishido Mitsuhira were famous for their martial arts style, while in Osaka, swords that were even more beautiful and appealing than those in Edo were made. These included Tsuda Sukehiro, Inoue Shinkai, Kawachi no Kami Kunisuke, Ikkanshi Tadatsuna, Echigo no Kami Kanesada, and Tatara Nagayuki. Other famous swordsmiths also appeared in local castle towns, including Kunikane of Sendai, Kanewaka of Kaga, Kunikiyo of Echizen, Teruhiro of Hiroshima, and Masatsune of Owari (Aichi Prefecture). These swords reflect the development of swordsmanship for one-on-one combat, measuring around 2 shaku 3 sun (approximately 70 cm), with an ordinary or slightly shallow curvature, and a narrow tip compared to the width at the base. However, after the Genroku period, the era of peace brought a significant decline in the production of swords, and there were no famous swordsmiths. Later, during the Kyoho period (1716-1736), the eighth shogun, Yoshimune, encouraged sword forging, but this only served to be a temporary trend.

[Nobuo Ogasawara]

Late Edo period

Swords from the end of the Edo period in particular are called "shinshinto," which refers to swords from the An'ei period (1772-1781) onward, when Suishinshi Masahide (Kawabe Gihachiro Masahide) appeared. Masahide's early days were a time when courtly samurai traditions such as the "Shuko Jyushu" were flourishing, and he produced swords that copied the glamorous Osaka shinto. However, he eventually became skeptical of shinto, and advocated a restorationist theory that all Japanese swords should return to the Kamakura period, which he put into practice. This theory was in line with the social climate of the time, and its followers spread throughout the country. Famous artisans of this period included Masahide's disciples, Taikei Naotane and Hosokawa Masayoshi, Minamoto Kiyomaro from Shinshu (Nagano prefecture) and his disciples Kurihara Nobuhide and Saito Kiyoto, as well as Koyama Munejiru, Ishido Korekazu, Sadakazu, Aizu Kanesada, and Masayoshi and Genpei from Satsuma.

[Nobuo Ogasawara]

After the Meiji Period

After the Meiji Restoration, the permission system for wearing swords in 1871 was followed by an edict banning swords, making swords no longer practical, and swordsmiths lost their jobs and became bladesmiths or field blacksmiths, or changed jobs, and some even made fake swords to make a living. Eventually, Gassan Sadakazu and Miyamoto Tadanori were selected as Imperial Household Artists, and efforts were made to protect the art of swordsmithing, but after the military sword boom of the Taisho and Showa periods, and with the end of World War II, the production of swords was banned. Currently, with certification from the Agency for Cultural Affairs, production is permitted under certain conditions in order to preserve the forging techniques of Japanese swords.

[Nobuo Ogasawara]

Forging the Japanese Sword

In order to make a Japanese sword that meets the three requirements of "not breaking, not bending, and cutting well," unique ingenuity is used in the forging method, but the manufacturing process can be characterized by the following three stages.

(1) The steel sheet is forged by folding it over.

(2) The soft core steel is folded over and over again until it is tempered, then placed inside the kawagane steel and beaten into the shape of a sword.

(3) The clay is removed, the blade is hardened, and the blade pattern is created.

There are various methods of forging and combining the shingane and kawagane, and they are called honsanmai, shihotsume, kobuse, makuri, etc.

[Nobuo Ogasawara]

Production process

(1) To make kawagane, first a piece of high-quality steel called tamagane is cut into pieces, beaten flat, and then hammered into small, even pieces.

(2) Using his ingenuity, the swordsmith makes grater out of scrap iron and cuts it into small pieces in the same way.

(3) These small pieces are piled up on the tip of a lever, then cut and hammered into a single square block. This process is called "Tsumiwakashi."

(4) The piled up wood is heated, stretched with a hammer, chiseled horizontally, and folded again vertically. This process is repeated 10 to 20 times. This is called "folding forging." The difference in the folding method results in different forged surfaces such as itame, mokume, and nashiji.

(5) To make the core steel, a small amount of tamahagane is added to soft pure iron (knife iron) and the steel is forged several times.

(6) The finished core iron is wrapped in the skin iron, which is then heated and hammered into a square rod shape. This is called "sunobetsu".

(7) The tip is cut off in a triangle from the ridge, heated, and stretched from the opposite edge towards the ridge to form the shape of a blade. This is called "Boshi-zukuri".

(8) The unformed blade is heated and flattened to make the blade thinner, then curved to create the rough shape of the sword. This is called "hizukuri."

(9) Further finishing is done with a chisel and file, followed by a simple rough grinding. This is called "rough finishing."

(10) A fire-resistant clay called yakibatsuchi is applied to the blade. This is called tsuchitori. The way the tsuchitori is applied determines the shape of the blade, whether it is straight or rough.

(11) After the clay has dried thoroughly, the forge is placed in a dark room, the blade is heated, and the appropriate temperature is determined by the reddened color of the blade. The blade is then instantly placed in a water tank. This is called "quenching."

[Nobuo Ogasawara]

Finishing

(1) The curvature is straightened out, rough sharpening is performed, the shape of the blade and the placement of the blade are adjusted, and the condition of the blade and the presence or absence of scratches are checked. This is called "Kajioshi".

(2) The shape of the tang is adjusted, the mekugi holes are drilled, and the file marks are made. This is called “tang finishing.”

(3) Finally, the swordsmith uses a chisel to carve the sword's name and date. This is called "meikiri."

This completes the process of making a sword, and the sword will be completed with the cooperation of the sharpener, scabbard maker, and silversmith (habaki maker).

[Nobuo Ogasawara]

The exterior of a Japanese sword

The exterior of a Japanese sword is called "sword fittings" or "koshirae." The term "sword fittings" refers to the process of lacquering the outside of the wooden sheath that holds the blade, fitting metal fittings, attaching a tsuba (guard), and attaching sharkskin to the handle and wrapping it with thread, while "koshirae" refers to attaching a tsuba with a transparent pattern to a polished sharkskin sheath, so ultimately they mean the same thing.

There are two types of tachi: gijo, worn when dressed for ceremonies such as when officially entering the palace, and heijo, worn on the battlefield, but both types of tachi mountings have thread wrapped around the hilt and the foot metal fittings on the scabbard. Also, utachi are worn on the waist with the blade facing up, but utachi mountings since the Muromachi period have a style in which the handle is wrapped with thread or leather. There are two types of mountings for waist swords, or short swords, called aikuchi and nomikuchi, but since the Kamakura period most have been aikuchi mountings. Daisho-sho mountings are a set of utachi and wakizashi with the same sheath paint and the same metal fittings, and have been used since the early modern period. Depending on the style, sword fittings are called by various names, such as kazatachi (decorative sword), thin sword, Hyogo Kusari Tachi, tweezer-shaped sword, black lacquer sword, plum blossom skin waist sword, nashiji (pear-textured sheathed sword), and gold noshi (wrapping)-tsuke utachi.

[Nobuo Ogasawara]

Appreciation of Japanese swords

Decorating the exterior of swords with gold, silver, or jewels is a common practice in both the East and the West, but when it comes to polishing the blade itself more carefully than for practical use, as an object of appreciation, the Japanese sword is unmatched. In the Engishiki, during the straight sword era, it is written, "One day for rough grinding, one day for tempering and medium grinding, one day for fine grinding, and one day for polishing," and this "polishing" is understood to mean work for the purpose of appreciation. As such polishing techniques developed, the various changes in the surface and blade pattern due to the combination of jigane became even more refined.

In Japan, especially among samurai, swords from ancient times were said to be "natural objects" and were presented as treasures or appreciated without any practical use, and within this tradition, in the late Muromachi period, families such as Honami and Takeya arose whose professions were to determine the identity of unsigned swords and to determine their authenticity. In particular, the Honami family held authority as a connoisseur of swords for the shogunate during the Edo period, and issued origami certificates such as "50 pieces of gold". This tradition continues to this day, and swords are appreciated while taking into account the appearance and forging methods of each era, the individuality of each swordsmith, and the historical background that produced the sword. When appreciating a sword, it is necessary to pay attention to (1) the shape and construction of the sword, (2) the identification of the intricate blade pattern, which can be broadly divided into straight and rough blades, (3) the identification of the surface of the blade, which clearly shows the forging method, and (4) the identification of the engravings on the blade, such as the bohi (straight grooves) and futasujihi (two grooves).

[Nobuo Ogasawara]

"Swords" by Ogasawara Nobuo (Hoikusha, Color Books)" ▽ "Complete Collection of Japanese Swords, supervised by Homma Junji and Sato Kanichi, 9 volumes (1966-68, Tokuma Shoten)" ▽ "Japanese Sword Lectures, 9 volumes (1966-69, Yuzankaku Publishing)" ▽ "The Story of Famous Japanese Swords" by Sato Kanichi (1962, Hakuohsha)"

Names of the various parts of a Japanese sword
©Katsuya Nishikawa ">

Names of the various parts of a Japanese sword

Types of Japanese Swords (Swords)
©Katsuya Nishikawa ">

Types of Japanese Swords (Swords)

Types of Japanese sword making
©Katsuya Nishikawa ">

Types of Japanese sword making

Types of Japanese sword blade patterns
©Katsuya Nishikawa ">

Types of Japanese sword blade patterns

Types of blade patterns on Japanese swords
©Katsuya Nishikawa ">

Types of blade patterns on Japanese swords

Names of each part of the sword (Hyogo Kusari Naga Engraving)
©Shogakukan ">

Names of each part of the sword (Hyogo Kusari Naga Engraving)

Names of Uchigatana Mountings
©Katsuya Nishikawa ">

Names of Uchigatana Mountings

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

Japanese:

日本刀とは日本の刀剣を総称し、太刀(たち)、刀、脇差(わきざし)、短刀などをいうが、広義には薙刀(なぎなた)、槍(やり)など刀鍛冶(かじ)によって製作されたものすべてを含める。普通、日本刀は西洋の剣(つるぎ)と異なって柄(つか)が長く、両手で使用する様式であり、片刃で反りをもち、長寸のものは鎬造(しのぎづくり)となる。軟鉄を心鉄(しんがね)に、鋼(はがね)を皮鉄(かわがね)にして包む独特の鍛造法が用いられ、機能性と造形的均整美に優れたものが多いが、さらに刀身全体でなく刃の部分だけに焼入れがなされる結果、刃文(はもん)（刃の文様）が現れ、鋼を鍛錬したことによる地肌(じはだ)（肌目(はだめ)）の文様とともに固有の美しさが表現されている。

［小笠原信夫］

日本刀の沿革

日本刀の歴史は古墳時代にまでさかのぼるが、以来、政治制度、戦闘方法、経済機構、生産技術、職人制度、風俗、習慣など多くの歴史的要因によって変遷してきた。

［小笠原信夫］

古代

日本刀の初期の形態は大陸から輸入されたもの、またこれに倣ってつくられたもので、直刀(ちょくとう)様式の片手柄であった。日本における刀剣の発達の特色は、銅剣、銅矛(ほこ)、銅戈(か)などの銅器と、鉄器との時代差があまりみられないことである。銅剣などが北九州地方に伝えられたのは紀元前2世紀ころの弥生(やよい)前期末であるが、紀元後2～3世紀の弥生後期には鉄剣、鉄戈あるいは素環頭大刀(すかんとうたち)などが早くも現れている（なお、古代の直刀を大刀と書き、後世の湾刀(わんとう)〈反りのある刀剣〉を太刀と書いて区別する）。

　やがて3世紀末からの古墳時代に入ると鉄製武器が主流を占めるが、5～6世紀までの大刀は片刃の直刀で平造(ひらづくり)様式（鎬のない片刃の造り）のものである。熊本県玉名郡和水(なごみ)町、江田船山(えたふなやま)古墳出土の銀錯銘(さくめい)大刀（国宝）はその代表的遺例である。刀装には、木製の柄や鞘(さや)の表面に金銅(こんどう)板をはり、そこに竜文、唐草文、円文、蕨手(わらびで)文などの彫刻や打出(うちだし)の文様がみられる。柄頭(つかがしら)は初期のころの素環にやがて単竜、双竜、獅噛(しがみ)、三葉(みつば)など各種の加飾がなされるようになり、形態も環頭のほかに円頭、方頭、圭(けい)頭、鳥首(とりくび)、頭椎(かぶつち)などが現れた。

　7世紀ごろには平造様式から切刃(きりは)造様式（鎬の線が刃のほうへ寄った造り）へと移っているが、これは中国隋(ずい)・唐時代につくられた新様とみられる。聖徳太子の佩刀(はいとう)と伝えられて大阪の四天王寺に伝来する丙子椒林(へいししょうりん)剣、七星(しちせい)剣（ともに国宝）は、大陸から舶載された切刃造大刀の代表例である。伝世の直刀はほとんどみられないが、正倉院宝物のなかには大刀55口(ふり)、手鉾(てぼこ)5口、鉾33口、刀子(とうす)70口が保管されており、その大刀の造込みは基本的には平造、切刃造、鋒両刃(きっさきもろは)造（先端部だけ両刃となった造り）の3種である。これらの目録である『東大寺献物帳』（別名『国家珍宝帳』）に唐大刀(からたち)と区別して記載された唐様大刀の名称を字句どおりに解釈すれば、前者は大陸製、後者はわが国における模作ということになる。刀装では、漆や彫金の巧技を用いた金銀鈿荘(でんそう)唐大刀が出色である。

［小笠原信夫］

平安時代

直刀から反りのある湾刀への移行期は明白ではないが、現存する作刀から推察して、平安中期以降と考えられる。すなわち坂上田村麻呂(さかのうえのたむらまろ)佩用と伝えられる鞍馬(くらま)寺所蔵の黒漆(くろうるし)大刀は切刃造直刀であるが、藤原秀郷(ひでさと)（俵藤太）佩用といわれる伊勢(いせ)神宮の錦包毛抜(にしきづつみけぬき)形太刀は柄部で強く反りがつき、鎬の稜線(りょうせん)がほぼ中央になった造込みで、これは日本刀（鎬造湾刀）様式が完成するまでの過渡的なものと解されている。日本刀の完成の時期は、おおむね律令(りつりょう)社会の班田(はんでん)制が崩れて荘園(しょうえん)制が発達した過程で新たな武士階級が発生成長していった時代と期を同じくしており、短甲(たんこう)（胴だけを覆う短い甲(よろい)）、挂甲(けいこう)（肩にかける甲）から大鎧(おおよろい)の完成へと変化した時代とも一致する。湾刀の日本刀様式は、物を切る場合に直刀より衝撃が少ないという利点があるが、作刀上は刀剣の刃方(はかた)の薄いほうを張らせて棟(むね)の厚いほうへ反らせ、さらに刃部に焼きを入れることが容易な技術ではない。したがって湾刀の出現は、馬上から断ち切る戦闘上の必然性のみならず、良質鉄資材の生産と鍛錬技術の進歩に負うところが多いと考えられる。また983年（永観1）、987年（永延1）には京中畿内(きない)で兵仗(へいじょう)（戦闘用の太刀のこと）の帯用を禁止していることからも、当時かなりの刀剣が一般に普及していたと考えられる。

　平安時代の太刀様式は、身幅は元に対して先が半分くらいに狭くなり、鋒（切先）は小さく、反りは腰元で強く反って先ではほとんど反らない感じのものとなる。茎(なかご)（柄に収まる部分）は先が細って反りがつき、なかには太刀拵(ごしらえ)の関係で雉子股(きじもも)型となるものがある。刃文は、前時代の直刀が単純で弱い直刃(すぐは)調で、沸(にえ)むらや乱刃(みだれば)など技術的に未熟なものであったのに比して、この時代の名刀といわれるものは直刃調ではあっても足(あし)・葉(よう)が交わったり、金筋(きんすじ)（沸がつながって線状になり、刃中に美しく光る文）が入るなど、小乱(こみだれ)調に細かく変化したものとなって技術の向上が歴然としている。平安後期には各地で多くの刀工の輩出をみるが、その代表的なものを列挙すれば次のとおりである。

●三条宗近(むねちか)　永延(えいえん)（987～989）ころに京三条に住したところから、三条小鍛冶(こかじ)の呼称がある。小鍛冶とは鉄材から製品をつくる者のことで、製鉄に従事する者を大鍛冶という。一門には吉家、兼永、国永、有成、近村などがいる。

●古備前友成(こびぜんともなり)・正恒(まさつね)　備前国（岡山県）は古くから刀剣最大の製作地であるが、その要因は中国山地からの鉄の産出による。この両者は永延あるいは承保(じょうほう)（1074～77）ごろともいわれるが、同名数工が鎌倉時代まで存在したとみられている。備前には鎌倉時代に則宗(のりむね)を祖として一文字派がおこるが、それ以前の備前物を総称して「古備前」と称する。

●伯耆安綱(ほうきやすつな)　中国山地を隔てて備前と反対側にある伯耆国（鳥取県）にも鉄が多く産出し、安綱は名工として名高い。一説に大同(だいどう)（806～810）ごろともいうが、永延説が正しい。

●三池光世(みいけみつよ)　筑後(ちくご)国（福岡県）三池の典太(てんた)光世は承保ごろの人といわれ、豊前(ぶぜん)国（福岡・大分県）の長円(ちょうえん)、豊後(ぶんご)国（大分県）の僧定秀(じょうしゅう)、さらに薩摩(さつま)国（鹿児島県）の行安(ゆきやす)などとともに九州鍛冶を代表する存在である。

［小笠原信夫］

鎌倉時代

鎌倉時代（1192～1333）の約150年間は、刀剣が大いに発展を遂げた時代であるが、その変遷過程からみて大きく50年ずつ3期に分けることができる。初期50年は、まだ平安時代の作風を継承した古雅なものが主流であるが、なかには大ぶりで豪壮なものが現れていることは見逃せない。鎌倉時代は社寺と公家(くげ)勢力に対する武家勢力の抗争が激しい時代で、刀剣史においても、寺院に隷属した鍛冶の存在が大きな役割を演じたが、特筆すべきは後鳥羽(ごとば)院番鍛冶（院に上番して1か月交替で御用を勤めた刀工）である。上皇は、京の粟田口(あわたぐち)派や、備前・備中(びっちゅう)から名工を召し出して月番を定めて鍛刀させ、自らも焠刃(さいじん)（焼入れ）したという。

　鎌倉中期になると、太刀は身幅が広く、平肉(ひらにく)がついて、先幅もあまり細らず、重ねの頑丈な体配で、鋒も中鋒が詰まって猪首(いくび)切先となって豪壮さを示している。刃文は山城(やましろ)（京都府）や備前に丁子(ちょうじ)刃の華やかな作風が生まれたが、大和(やまと)系の鍛冶にはじみな作風が多い。これは、山城や備前の刀剣が販売に供せられたのに対し、大和鍛冶は社寺に隷属して伝統を踏襲したためとみられる。短刀（この呼称は近世に至るまでみられず、古くは腰刀(こしがたな)または小刀(ちいさがたな)という）は実用本位の消耗品であったためか、早い時期には遺例も少なく特筆すべきものはないが、この時期になると名作も多くなる。その多くは平造、内反りの尋常なもので、茎はまっすぐなものと、振袖(ふりそで)茎と称する棟方に大きく反ったものとがある。薙刀は前時代から絵巻物などに散見されるが、鎌倉中期のものはいずれも反りが少なく頭の張らない姿のものである。槍はほとんどみられない。剣(けん)は短刀同様の寸法だが、これは武器ではなく密教の法具として用いられた。

　1274年（文永11）と81年（弘安4）の二度にわたる元(げん)の来襲により、幕府は九州沿岸の防備に努めて戦力を養成した。この元寇(げんこう)がわが国の戦術や武器に与えた影響は大きく、鎌倉末期の刀剣は豪壮さが強調され、山城・備前の作風にも刃文の華やかさが減少している。一方、相州（神奈川県）の幕府の根拠地鎌倉では、新藤五国光(しんとうごくにみつ)とその弟子とされる正宗(まさむね)によって相州伝の作風が完成した。これは、硬軟の地鉄(じがね)を組み合わせて、地景(ちけい)・金筋などの働きと湾(のた)れ刃を基調とした大模様の刃文による沸の美しさを表現したもので、とくに正宗の作風は全国的に影響を与え、後世まで日本刀美の一典型とされ続けた。

　総じてわが国刀剣史の白眉(はくび)とされる鎌倉時代に活躍した刀工の系譜としては、次のものが特筆される。

●山城鍛冶　京には三条派のあと粟田口派が現れ、国友・久国・国安・国清・有国・国綱の6兄弟、のちに国吉・吉光などを数える。後期には粟田口にかわって国行・国俊・国光・国次など来(らい)派が栄えたが、綾小路定利(あやのこうじさだとし)や了戒も著名である。

●備前鍛冶　一文字派が多数の名工を輩出しており、華やかな丁子刃の作風に特色があり、吉房・助真(すけざね)・則房(のりふさ)などが代表工である。中期を過ぎたころから長船(おさふね)派が隆盛し、光忠(みつただ)に始まって長光・景光・兼光と続き、同派を名のる鍛冶はさらに室町期から江戸末期にまで及んでいる。

●大和鍛冶　千手(せんじゅ)院・当麻(たいま)・手掻(てがい)・保昌(ほうしょう)・尻懸(しっかけ)の5派が有名である。千手院・手掻・尻懸は奈良、当麻・保昌は南大和の鍛冶で、いずれも寺院との関係が深い。

●相州鍛冶　相州には備前から国宗・助真が、山城から国綱がきたというが明らかではなく、事実上は新藤五国光に始まり、その弟子行光・正宗・則重(のりしげ)によって作風が完成されている。

［小笠原信夫］

南北朝時代

この期は60年間ほどにすぎないが、豪壮頑健さが最大限に誇張され、刀剣史上大きな変遷期となった。野(の)太刀・背負(せおい)太刀と称される3尺（約91センチメートル）にも余る身幅の広いものも現れたが、これらは後世磨(す)り上げられて打刀(うちがたな)（腰に差す戦闘用の刀）に直されたものが多く、そのため生茎(うぶなかご)（鍛刀時のままの茎）のものはまれで、大磨上(おおすりあ)げのために無銘となったものが多い。大太刀とは別に、南北朝後期には小ぶりな太刀も現れ、またこのころから打刀が太刀と同様の寸法にまで大きくなって流行し始め、短刀も身幅が広く反りがついて、1尺を超える大ぶりとなった。こうした趨勢(すうせい)は次に述べる各地の刀工の格好の舞台となったが、この期の刀剣に刻まれた南朝年号と北朝年号は、それぞれの地域の朝廷支配を知る資料ともなっている。

●相州鍛冶　正宗のあとに貞宗(さだむね)、さらに広光・秋広がいて、特色のある皆焼(ひたつら)刃をみせている。

●山城鍛冶　来派にかわって工房的性格の強い信国(のぶくに)鍛冶がおこり、同名数工が室町時代に及んでいる。長谷部(はせべ)派は国重と国信が有名で、相州伝に近い皆焼刃の作風である。

●美濃(みの)鍛冶　南北朝以降大いに繁栄したこの一派の始祖は、美濃（岐阜県）志津の地へ移住して兼氏(かねうじ)と称した大和手掻派の包氏(かねうじ)とされ、正宗に学んだ人といわれる。さらに一派の弟子が直江（養老町）の地に移り直江志津をおこした。また越前(えちぜん)（福井県）敦賀(つるが)から関(せき)の地に金重が移り、関鍛冶の祖となっている。

●備前鍛冶　兼光を頭領とする長船派はいくつかの系統に分かれたらしく、南朝年号を銘する長義(ちょうぎ)、大宮派という盛景、小反(こぞり)派という倫光(ともみつ)・秀光(ひでみつ)・政光(まさみつ)などがいるが、作風は長義が優れている。

●備中鍛冶　備中（岡山県）には鎌倉初期から青江鍛冶がいたが、この時代の青江物は末(すえ)青江といい、次吉・次直などが直刃や逆(さかさ)丁子に手腕をみせた。

　そのほか、筑前(ちくぜん)（福岡県）の左文字の一門、肥後（熊本県）の延寿の一門も著名である。

［小笠原信夫］

室町時代

1392年（明徳3）の南北朝の統一によって室町期に入ると、刀剣は南北朝時代の大太刀が廃れ、鎌倉期様式に近い太刀が現れている。しかし一方では、前時代から下級武士が差し始めた打刀がしだいに普及し、太刀にかわって刀剣の主流を占めていった。徒(かち)の下士や兵卒用の甲冑(かっちゅう)（胴丸や腹巻）が高級化して、上級武士にまで着用されるようになったのと同じ現象である。また、槍の普及も目覚ましく、弓矢とともに主要武器となった。こうしたなかで、1尺3寸（約40センチメートル）から一尺七～八寸の鎬造の脇差が多数製作された。これらは太刀の差し添えの打刀であったろうが、後期には長さも2尺前後となり、先反りの強い、時代の特色をよく示した様式を実現している。しかしその一方では、戦乱の多発を反映して数打物(かずうちもの)・束刀(たばがたな)と称される粗悪な刀剣も多作された。

　1543年（天文12）の鉄砲伝来は、刀剣や甲冑はおろか、城郭や戦術、さらには社会構造までも変貌(へんぼう)させていったが、こうした変革のなかでかえって多数の刀鍛冶が輩出した。すなわち越中(えっちゅう)（富山県）宇多(うだ)、加賀（石川県）藤島、駿河(するが)（静岡県）島田、伊勢(いせ)（三重県）千子(せんご)、武州（埼玉県）下原(したはら)、阿波(あわ)（徳島県）海部(かいふ)、豊後（大分県）高田などであるが、とくに次の2派は卓越していた。

●美濃鍛冶　室町期最大の刀剣生産地といえば、東では美濃の関であるが、これはこの地に春日(かすが)神社を本所(ほんじょ)とした座組織があったためとみられる。美濃鍛冶はいずれも「兼」字を冠しており、和泉守(いずみのかみ)兼定・兼房・兼元・兼常などが名高い。また関鍛冶は、各地へ移住して鍛刀しているのも特色である。

●備前鍛冶　応永(おうえい)期（1394～1428）の備前鍛冶を応永備前といい、盛光(もりみつ)・康光(やすみつ)の名がよく知られる。室町末期の備前鍛冶を末備前と称し、代表工は勝光・宗光・与三左衛門尉祐定(すけさだ)・孫右衛門尉清光(きよみつ)などである。

［小笠原信夫］

桃山時代

刀剣界では一般に慶長(けいちょう)（1596～1615）を境に、これ以前のものを古刀(ことう)、以後のものを新刀と呼び習わしている。これは、豊臣(とよとみ)秀吉による刀狩が、それまで量産された数打物・束刀といわれる粗悪刀を駆逐した結果となり、作風の一変したものが生まれるに至ったためである。なかには鎌倉・南北朝時代の古名刀を模範としたものも現れ、新しくできた大名城下町に刀鍛冶が定住するようにもなった。慶長から元和(げんな)（1615～24）期の有名刀工には、京の堀川国広・正弘(まさひろ)・国路(くにみち)・埋忠明寿(うめただみょうじゅ)、三品(さんぴん)派の金道・吉道・正俊、肥前（佐賀県）の忠吉とその一門、南紀の重国、越前の康継、江戸の繁慶(はんけい)などがいる。この期には鎌倉・南北朝期の大きな太刀を磨り上げて打刀に直したものがあり、新たに製作された刀剣もこれらの姿に似て身幅が広く、鋒が伸びて反りの浅い体配となる。とくに相州正宗・貞宗が理想とされた。

［小笠原信夫］

江戸時代

寛永(かんえい)年間（1624～44）から元禄(げんろく)（1688～1704）までは武家の全盛時代で、新刀の隆盛期であった。江戸・大坂を中心に刀鍛冶が活躍し、江戸では武張った作風に特色をもつ長曽禰虎徹(ながそねこてつ)、法城寺正弘、大和守安定(やまとのかみやすさだ)、上総介(かずさのすけ)兼重、石堂光平(みつひら)らが著名で、大坂では江戸の作風よりも一段と美感に訴える華麗な作刀がなされている。津田助広、井上真改(しんかい)、河内(かわち)守国助、一竿子(いっかんし)忠綱、越後守包貞(かねさだ)、多々良(たたら)長幸らである。ほかに地方城下町にも名工が現れており、仙台の国包(くにかね)、加賀の兼若、越前国清、広島の輝広、尾張(おわり)（愛知県）の政常らが名高い。これらの作刀は、一対一で戦う剣術の発達を反映して、寸法は2尺3寸（約70センチメートル）前後あり、反りが尋常ないしやや浅く、元幅に対して先幅の細ったものとなっている。しかし、元禄を過ぎると泰平の世を受けて刀剣の製作は著しく減少し、名のある刀工もみない。後の享保(きょうほう)年間（1716～36）に8代将軍吉宗(よしむね)によって鍛刀が奨励されたが、一時的なものに終わっている。

［小笠原信夫］

幕末期

とくに幕末期の刀剣を「新々刀(しんしんとう)」と称するが、これは水心子(すいしんし)正秀（川部儀八郎正秀）の出現した安永(あんえい)年間（1772～81）以降の時代の刀剣をいう。正秀の初期は『集古十種』など有職(ゆうそく)故実の盛んな時代であり、華やかな大坂新刀を写したものを製作していたが、やがて新刀に疑問をもち、日本刀はすべからく鎌倉の昔に復すべきであるという復古説を唱え、それを実践するに至った。この説は時の世相とも一致し、その傾倒者は全国に広まっていったが、この期の有名工には正秀の弟子の大慶直胤(たいけいなおたね)・細川正義、信州（長野県）出身の源清麿(きよまろ)とその弟子の栗原(くりはら)信秀・斎藤清人(きよんど)、あるいは固山(こやま)宗次、石堂是一(これかず)、左行秀、会津兼定、薩摩の正良(まさよし)・元平(もとひら)らが数えられる。

［小笠原信夫］

明治以降

維新後は、明治4年（1871）の佩刀の許可制からさらに廃刀令へと進み、刀剣は実用性を失い、刀工も職を失って刃物鍛冶や野鍛冶になったり、転職したり、なかには偽物をつくって細々と生計をたてる例もあった。やがて月山貞一(がっさんさだかず)と宮本包則(ただのり)が帝室技芸員に選ばれてから鍛刀の技の保護が図られたが、大正・昭和の軍刀ブームののちは、第二次世界大戦の終結とともに刀剣の製作は禁止された。現在では文化庁の認証により、日本刀の鍛錬技術保存のための製作が条件付きで認められている。

［小笠原信夫］

日本刀の鍛錬法

日本刀は「折れず、曲がらず、よく切れる」という三つの条件を満たすために、その鍛錬法には独特のくふうがなされているが、製作工程からみると次の3段階に特徴がある。

（1）皮鉄(かわがね)を折り返しながら鍛錬する。

（2）軟らかい心鉄(しんがね)を何度も折り返して鍛錬し、皮鉄の中に入れ、刀剣の形に打ち延ばす。

（3）土取りを行って焼入れをし、刃文をつくる。

　この鍛錬の方法、心鉄と皮鉄の組合せ方法には種々あって、本三枚、四方詰、甲伏(こうぶせ)、捲(まくり)などの名でよばれている。

［小笠原信夫］

製作工程

（1）皮鉄をつくるには、まず玉鋼(たまがね)と称する優良な鋼を爍(わか)して打ち平(ひら)めたものに鎚(つち)を加えて、平均に小割りにする。

（2）刀匠のくふうにより、古鉄などを用いて卸鉄(おろしがね)をつくり、同様に小割りにする。

（3）これらの小割りにしたものを梃子(てこ)の先に積み重ね、さらに爍して鎚を加え、一つの四角い塊にする。この工程を「積爍(つみわかし)」という。

（4）積爍したものを熱し、鎚を加えて延ばしては横に鏨(たがね)を入れて折り返し、また縦に鏨を入れて折り返す。この作業を10数回から20数回行う。これを「折返し鍛錬」という。この折返しの方法の違いにより、板目、杢(もく)目、梨地(なしじ)などの鍛え肌の違いとなる。

（5）心鉄をつくるには、軟らかい純鉄（包丁鉄）にわずかに玉鋼を加え、数回折返し鍛錬を行う。

（6）できた心鉄を、先の皮鉄で包み、これを熱して角の棒状に打ち延ばしていく。これを「素延(すの)べ」という。

（7）先を棟のほうから三角に切り落とし、加熱して反対の刃方から棟方へ寄せて打ち延ばし、鋒(きっさき)の形をつくる。これを「帽子造(ぼうしづくり)」という。

（8）素延べのものに加熱して打ち平めて刃方を薄くし、さらに反りをつけ、だいたいの刀の形をつくる。これを「火造(ひづくり)」という。

（9）鏟(せん)と鑢(やすり)でさらに仕上げを加え、簡単に荒研(と)ぎをする。これを「荒仕上げ」という。

（10）焼刃土(やきばつち)と称する耐火粘土性のものを刀身に塗る。これを「土取り」という。土取りの仕方により、直刃や乱刃の刃文が決まる。

（11）土取りの土がよく乾いてから、鍛冶場を暗室にして、刀身を加熱し、その赤く焼けた色により適当な熱度を知り、瞬間的に水槽の中に入れる。これを「焼入(やきい)れ」という。

［小笠原信夫］

仕上げ

（1）反りを整え、荒研ぎを加えて、地刃の姿や肉置(にくお)きを整え、焼刃の状態、きずの有無などを確かめる。これを「鍛冶押(かじおし)」という。

（2）茎の形を整え、目釘孔(めくぎあな)をあけ、鑢目(やすりめ)をたてる。これを「茎仕上げ」という。

（3）最後に鏨で自らの刀匠銘や年紀を切る。これを「銘切り」という。

　以上で刀剣の製作工程が終わり、あとは研師、鞘(さや)師、白金師（鎺(はばき)師）の協力を得て完成する。

［小笠原信夫］

日本刀の外装

日本刀の外装のことを「刀装(とうそう)」または「拵(こしらえ)」という。刀装の語は、刀身を入れる木製の鞘の外側を漆塗りにして金具をはめ、鐔(つば)をつけ、また柄に鮫(さめ)皮を張って糸などで巻いて装うことを意味し、また拵は、研出(とぎだし)鮫の鞘に透(すか)し文様の鐔をつけたりしてこしらえるということであって、結果的には同じことを意味する。

　太刀には、公式に昇殿するなど儀式の装束をしたときに佩(は)く儀仗(ぎじょう)と、戦陣で佩用する兵仗(へいじょう)とがあるが、いずれの太刀の拵も柄と鞘の足金物(あしがなもの)の部分まで糸巻きにしている。また、打刀は刃を上にして腰に差す様式であるが、室町時代以後の打刀の拵は柄を糸または革で巻く形式である。腰刀すなわち短刀の拵には、合口(あいくち)と呑口(のみくち)の二様があるが、鎌倉時代以降はほとんど合口の拵となっている。大小拵というのは、打刀と脇差を同じ鞘塗り、同じ金具でそろえて1組としたもので、近世になって行われている。刀装はその形式によって、飾剣(かざたち)、細太刀、兵庫鎖太刀、毛抜形太刀、黒漆太刀、梅花皮腰刀、梨地(なしじ)鞘打刀、金熨斗(のし)付打刀など、さまざまな名称でよばれている。

［小笠原信夫］

日本刀の鑑賞

刀剣に金銀や玉(ぎょく)を用いて外装を美しく飾ることは洋の東西を問わず広くなされているが、刀身そのものを実用のため以上に入念に研磨して鑑賞の対象とした点では、日本刀の右に出るものはない。直刀時代の『延喜式(えんぎしき)』に「麁砥(あらと)磨一日、焼并(ならびに)中磨一日、精磨一日、瑩(みがき)一日」とあるが、この「瑩」というのは鑑賞を目的とした仕事であると解される。こうした研磨の技が発達し、地鉄(じがね)の組合せによる地肌や刃文のさまざまな変化が、さらに精細を極めるようになったといえよう。

　わが国では、とくに武家の間で古い時代の刀剣が「可然物(しかるべきもの)」といわれ、宝物として献上されたり、実用を離れて鑑賞されたが、こうした伝統のなかで室町後期には無銘の作にだれの作かの極めをつけたり、その真偽を断定するのを職業とする本阿弥(ほんあみ)、竹屋などという家が興っている。とくに本阿弥家は江戸時代には幕府の目利所(めききどころ)として権威をもち、「代金子五十枚」などという折紙を出したりした。こうした伝統は今日にも及んでおり、各時代の体配や鍛法、刀工各人の個性、またその刀剣を生んだ歴史性を加味しながら賞美することが行われている。鑑賞に際しては、（1）刀剣の姿や造り、（2）直刃・乱刃に大別される精妙な刃文の鑑別、（3）鍛錬法を如実に示す地肌の鑑別、（4）棒樋(ぼうひ)・二筋樋(ふたすじひ)をはじめとする刀身彫刻による鑑別、などに留意する必要がある。

［小笠原信夫］

『小笠原信夫著『刀剣』（保育社・カラーブックス）』▽『本間順治・佐藤貫一監修『日本刀全集』全9巻（1966～68・徳間書店）』▽『『日本刀講座』全9巻（1966～69・雄山閣出版）』▽『佐藤貫一著『日本名刀物語』（1962・白凰社）』