The following is a brief outline of the five major schools of the Kotô period. They consist of the Yamashiro school, the Yamato school, the Bizen school, the Mino school, and the Sôshû school.
SUGATA: The sugata of the Yamashiro school during the late Heian and early Kamakura eras was narrow and graceful. They had a wide mihaba and that narrowed to a ko-kissaki (this is called fumbari). In the middle to late Kamakura periods, the sugata changed from gentle to grand. The kissaki became larger and stouter (ikubi kissaki) and the fumbari (narrowing of the blade) decreased so that even at the yokote the blade was wide. This was the time that the Bizen den was at its peak and it greatly influenced these changes in the sugata of the Yamashiro school. From the Nanbokucho period and into the Muromachi period, the Yamashiro school gradually disappeared, but it remained the influence for several of the later sword schools during the Shinto period.
JIHADA: Most common is ko-mokume-generally in a much finer grain pattern than that of the other schools. It will contain chikei and ji-nie. Often early schools such as the Awataguchi will have a beautiful utsuri and the blades will be very close in appearance to those of the ko-Bizen school. In the mid to late Kamakura period, the jihada becomes chu-mokume or o-mokume, rather than ko-mokume hada.
HAMON: During the Kamakura era there were two patterns of hamon found on Yamashiro swords. The first was a ko-chôji midare based on suguha, mixed with ko-nie, displaying splendid activity. The second type was a wide suguha chôji-midare based on suguha with ashi and nie. This type is readily seen in the Rai school and was influenced by the Bizen school. In the hamon of the mid to late Kamakura era we see basic suguha mixed with a small amount of large midare, with a good deal of activity inside the hamon. We also see a Kyo-chôji midare. This is chôji midare based on suguha and the yakigashira (top of the midare) is inclined to be flat.
NAKAGO: Long and tapered. The jiri (tip of the nakago) on blades made before 700 years ago is kuri. Those made after 700 years ago tend to be kuri and kengyo.
SUGATA: The development of sword making in the Yamato area Japan was closely linked to the area’s proximity to the capital of Nara. Furthermore, swordsmiths’ prosperity depended on their relationship with the temples with which they were affiliated. During the late Heian and early Kamakura eras, the shape of the Yamato blades was narrow and graceful. They were thicker than Yamashiro with a much higher shinogi. By the end of the Kamakura era the five Yamato schools of sword making had mostly disappeared (except the Hosho school) and Yamato blades from the Nanbokucho era are very rare. The Yamato tradition, however, exercised great influence of many other schools such as the Shizu, Akasaka Senjuin, Ino, Uda, Asako, Iruka, Sudo, Mihara, Kanabo, and others.
JIHADA: The jihada of the Yamato school of the middle Kamakura era will be inferior to the fine jihada of the Yamashiro school of the same time. It will be composed of masame- hada, but even when the jihada is mokume-hada, it tends to be a nagare-hada combined with a masame-hada of a certain fineness. There will always be masame-hada in the shinoji-ji. The Taima school will have a well-forged fine mokume-hada mixed with itame-hada, chikei, and yubashiri appears. Only the Hosho school will have a pure masame-hada every time. Ji-nie will be abundant
HAMON: The hamon is based on suguha in nie deki, as it is in the Yamashiro tradition, but vertical activities such as nijuba, uchinoke, and hakikake appear along the hamon. Nie are larger than in the Yamashiro tradition, and more highly reflective. The amount of nie on an individual sword will vary between abundant or scarce. Occasionally, especially in the Senjuin school, the suguha hotsure will be mixed in with ko-chôji and ko-midare. As with the other schools, there will be nijuba, uchinoke, kuichigaiba, kinsuji, and hakikake.
NAKAGO: The nakagojiri will vary somewhat by school. The Taima and Shikkake schools will be iri-yamagata, others are kuirgata. The yasurime will be takanoha, higaki, kiri or katte sagari depending on the school.
NOTES: Major Yamato Schools:
SUGATA: Graceful blades with koshi-zori (deepest part of the curve in the lower third of the blade) is taken to be a characteristic of the Bizen den. There is a deep koshi-zori in many Ko-Bizen blades of the late Heian and early Kamakura eras resembling the blades of the Yamashiro tradition of the same time. During the middle and late Kamakura era, the brilliant Bizen tradition is established by the Ichimonji and Osafune schools. The sugata becomes grander than those of earlier periods and we start to see swords with the stout and strong ikubi kissaki. We also see the gentle sugata of earlier times resembling the works of the Yamashiro den. The Nanbokucho era brings exaggerated sugata where we see blades reaching a length of up to three feet with large extended kissaki. During the Muromachi era blade length becomes shorter and the sori moves forward on the blade creating a saki-zori. We see the birth of the short uchi-katana of just about 24 inches which could be wielded with one hand. The Bizen school continued into the Shinto and Shinshinto eras.
JIHADA: Mainly composed of a combination of itame-hada and mokume-hada, there is ko-mokume, chu-mokume, and o-mokume and it is usually combined with itame-hada. Utsuri in a variety of forms is frequently seen in the ji.
HAMON: Mainly midareba in nioi-deki. There is chôji-midare in many varieties and gunome-midare. The robust juka-chôji of the Fukuoka Ichimonji school of the Kamakura era is thought by many to be the work of the Bizen school at its zenith. Suguha is also often seen, particularly in the Muromachi era and later. Nie is of medium size, plentiful along the line of nioi but it is rarely found as ji-nie.
NAKAGO: Older pieces tend to be long and slender, there is niku on the hira (the hira is rounded) and they are well proportioned. With the passage of time, they gradually became thick and short with parallel sides and after Oei, (1394-1428) there were many that were so short that at first glance they look unbalanced. These are called uchi-gatana and generally used with one hand. The nakago-jiri is usually kuri.
SUGATA: During the early Mino period, the sugata was pretty much standard for the end of the Kamakura era. The mihaba was not very wide and the kissaki was a chu-kissaki at most. From the middle of the Nanbokucho era through the early Muromachi era, the mihaba becomes wide and the kissaki becomes large. Tantô are rare. Hira-zukuri ko-wakizashi with a wide mihaba and sori are popular. During the later Mino era (the sue-seki school), there developed two katana sugata. One has a wider shinogi-ji than usual, despite its relatively narrow mihaba. The other has a wider mihaba, narrower shinogi-ji, and a deep saki-zori. Shobu-zukuri tanto, yari, and naginata are often seen. In tantô, there are three general sizes; one about 20 cm, one about 26 cm, and one over 30 cm.
JIHADA: The early Mino period will fine o-mokume hada combining with some masame-hada with chikei and abundant ji-nie. The jihada is clear and does not appear whitish. During the middle Mino period, we find a mokume-hada combined with masame-hada that stands out near the hamon on in the shinogi-ji. The jigane looks somewhat whitish and hard. The later Minho period will find swords with a hard jigane. The jigane will be dark, almost blackish. The ji will be a coarse mokume-hada and the hada in the shinogi-ji will be masame.
HAMON: The early period will find swords done in nie-deki, with abundant nie and thick nioi. The nie and nioi are bright and large nie will be found sometimes. Widths vary greatly. The pattern is o-midare, o-gunome midare, notare-midare, etc. Kuzure, inazuma, sunagashi, and kinsuji will be found. In the middle period, the hamon will be wide and o-midare or gunome-midare, with nie. The hamon has a deformed area that produces togari-ba and sunagashi. The later period finds togari gunome done in regular intervals of three peaks. This is the famous sanbon-sugi (three cypress trees) for which the Mino school is famous. Other patterns of hamon such as o-notare, yahazu-midare, hitatsura, etc. will be found. Occasionally even suguba can also be found from time to time. Note, however, that in all Mino den hamon somewhere the there will always be at least one small peaked midare (togari). This is even true of suguba (straight) temper.
NAKAGO: The nakago of the early period will be kuri-jiri, among the tantô, furisode with dep sori is sometimes seen. Yasurime are kiri or shallow katte sagari. The yasurime of the middle period can be kiri, katte sagari, or sometimes higaki. During the later Mino period, kurijiri is popular and the yasurime is generally higaki or takanoha.
SUGATA: The Sôshû den was founded in the city of Kamakura and was the last of the five major Koto schools to come along. It was founded in the late 13th century by Shintogo Kunimitsu whose roots were in the Awataguchi school of the Yamashiro tradition. Thus, the early Sôshû works of the late Kamakura and early Nanbokucho era show the influence of the Yamashiro tradition of the same time. The sugata tended to be wide, often with a larger kissaki. Generally, they had a torii sori during the early and middle periods of Sôshû workmanship and later changed to a saki-zori in the Muromachi era.
JIHADA: The grain is most often a very fine and compact itame-hada mixed with a mokume-hada. Sometimes it will be combined with o-hada. There will be profuse nie and ara-nie throughout the ji. Often it will take the form of hitatsura or “full temper”, particularly in the Middle period of Sôshû workmanship during the Nanbokucho era.
HAMON: The hamon will be in a variety of forms. Early Sôshû works are strongly influenced by the Yamashiro school so we find a fine mokume-hada with abundant ji-nie and a rounded yubashiri. Others will be wide and based on suguha but mixed with notare and nie kuzure. Often it will take the form of hitatsura or “full temper”, particularly in the Middle period of Sôshû workmanship during the Nanbokucho era.
NAKAGO: Probably the most common nakago shape is the funa-gata. Another typical shape is called tanago-bara. (This resembles the abdomen of the tanago fish found in the rivers of Sôshû province). The jiri is commonly kengyo.