Rai Kunitsugu Katana

Rai Kunitsugu

periodEnd of Kamakura (ca. 1326)
designationNBTHK Juyo Token Katana
ratingSai-jo saku
nagasa71.6 cm
sori2.0 cm
motohaba3.35 cm
sakihaba2.65 cm
kissaki5.3 cm
nakago nagasa18.6 cm
nakago sori0.1 cm
price -sold-

The Yamashiro Rai school was founded in legend by a smith named Kuniyoshi, who is considered to have come from Korea. The character Rai (来) means come, and the implication is that this relates to the founder coming from overseas to Japan. There are no extant works by Rai Kuniyoshi though, so in practical terms the founder of Rai is considered to be Rai Kuniyuki. His style is purely mid Kamakura, making majestic broad blades with dense choji hamon.

The son of Rai Kuniyuki is the smith referred to as Niji Kunitoshi (i.e. two-character Kunitoshi). Signed work by this smith is generally in the style of his father, utilizing choji in the hamon and with the wide blade and ikubi kissaki of the times. There is some confusion because following Niji Kunitoshi is the smith referred to as Rai Kunitoshi. The work of Rai Kunitoshi in contrast is more elegant and less flamboyant, often featuring suguba and a tapering sugata. When his signature is found, it takes the form of three characters reading 来國俊 (Rai Kunitoshi). He can alternately be called Sanji Kunitoshi (three character Kunitoshi).

Luckily for us, there is a dated work of 1315 by Rai Kunitoshi where he placed his age of 75 years on the nakago. Dr. Honma Junji was the founder of the NBTHK and a renowned expert on Nihonto. He wrote this about Rai Kunitoshi in Great Masterpieces of Japanese Art Swords:

[In regards to the dated work at 75 years of age] ... Together with the date inscription, this is an important reference material for the study of Rai works. Of those signed works by Rai Kunitoshi which have been examined to date, the earliest is dated Sho-o 3-nen (at the age of fifty), and [the latest is] Genkyo Gan-nen (at the age of eighty-one).

Detail of Juyo Rai Kunitsugu Katana

Fifty years of age would seem to be unusually late for a smith of grandmaster skill to appear on the scene. There is dated work by Niji Kunitoshi, a famous one with the date of 1278, and one with the date of 1286. There is no other dated work by Niji Kunitoshi that I am aware of, and if we are to believe that these works are by Rai Kunitoshi at the beginning of his career then this would make him 38 and 46 years old at their time of production, which would allow him decades of experience to accumulate the skill he displays under the old signature style.

Fujishiro has weighed in on the one smith / two smith theory as well, writing:

The theory that two kanji Kunitoshi and Rai Kunitoshi were separate persons is a theory that ignores the style changes of the times (See Nagamitsu). In the Showa Gonen Book section of the Kanchiin Hon, beneath a Kunitoshi two kanji signature nakago, it says, Rai Magotaro Nyudo, kogiri yasuri, becomes wide sugu yakiba, and this is a record which coincides with the time when Kunitoshi and Kunimitsu nado were living. What became clear in later years was that it was discovered that his works covered a long period of time, due to works inscribed with Showa Yonen Nanajugosai (Showa 4, 75 years of age) and Bunpo Gannen Seinen nanajuhachi (Bunpo 1 age 78). Also, the two character Kunitoshi period coincides with the prime of his life, and backs up the one generation theory.

Furthermore, he indicates that Rai Kunitoshi is one of the smiths who was famous in his own time. He writes:

It is not hard to imagine why the kaji Kunitoshi, Kunimitsu, and father and son Kunitsugu were famous and prospered in their time. Among the names of the swordsmiths that have been handed down to the present day, there are two cases, the one in which their fame was circulated about while they were still living, and those which became famous after they died. It is probably reasonable to consider Kunitoshi nado among the former.

Rai Kunitoshi has long been considered to be one of the top three tanto makers of all time, and stands with Awataguchi Yoshimitsu and Shintogo Kunimitsu in this elite club. The form of his tanto are considered to have achieved perfection and are the archetype used to describe late Kamakura tanto work.

Detail of Juyo Rai Kunitsugu Katana
Rai Kunitsugu Katana Rai Daimei

Rai School

The time of Rai Kunitoshi was wildly successful, and he is written about shortly after his death as one of the pre-eminent smiths of his time. The Rai school spread from his forge into various provinces such as Echizen, Higo (via Enju), Sagami, and Settsu.

Kunitoshi's oldest son is Ryokai who is said to be fathered when Kunitoshi was 17. After this follow Rai Kunimitsu, Rai Kunisue, Rai Kuninaga, Rai Kunitsugu, Rai Kunizane, Rai Kunimune, and Rai Tomokuni. Other students and descendants include Mitsukane who came over from the Nagamitsu group, Rai Mitsushige, Rai Mitsusada, Rai Sueyuki, Rai Kuniyasu, Rai Sanemune, and others. Furthermore there are likely two generations or more of Rai Kunimitsu and Rai Kuninaga. Signed works of some of the Rai smiths are very rare, or only exist in oshigata at this point in time. From all of this we can see that Rai Kunitoshi was a very busy man.

Kunimitsu is generally held to be the oldest of his students with the exception of Ryokai, and Kunitoshi, Kunimitsu and Kunitsugu all used Minamoto in rare examples of their mei. All of Kunimitsu, Kunitsugu and Kuninaga had a code of sorts when they signed their names and when they made daimei for Rai Kunitoshi and signed his name. Because of this we can decode which signed Rai Kunitoshi works are made by the students.

Rai Kunisue

Rai Kunisue is said to be the third son or possibly younger brother of Rai Kunitoshi and carries the nickname of Hiki-Rai. He is supposed to be active around 1288 and the earliest extant sword book Kanchiin-bon Meizukushi states that Kunisue was responsible for opening the Kamakura branch of the Rai school in Hikigayatsu and cites his death at the age of 30. Due to the extreme age of this book (written in 1316) and it being contemporary to these events, we can accept it as reliable information. The one remaining example of his work is quite similar to Rai Kunitoshi as one might expect and is ranked Juyo Bijutsuhin.

Rai Kunisue signed tachi, Juyo Bijutsuhin
Rai Kunisue signed tachi, Juyo Bijutsuhin
Kokuho Rai Kunitsugu
Kokuho Rai Kunitsugu

Rai Kunitsugu

Rai Kunitsugu is said to have worked in this Kamakura branch of the Rai school, and his work is the most distinctive in the group. Some of them are traditionally Rai in style, but others are strongly influenced by Soshu. Kunitsugu is included in the legend of the Masamune Juttetsu (10 great students of Masamune). He carries the nickname Kamakura Rai which may predate this, or may be because of this. He has a signing habit of placing his mei at the bottom of the nakago on tanto and this is quite similar to the Kamakura smiths such as Hiromitsu and Hasebe, and furthermore one oshigata exists of a signature example including Kamakura as the place of construction. He had a son Rai Kunihide and a grandson Rai Hidetsugu, who followed in the school taking it up to the Oei period.

The following is specifically about each individual. First, Rai Kunitsugu is acceptable [to be considered as a student of Masamune] chronologically because of the existence of Gentoku and Shokei dates given in his works. His workmanship, especially midare, is the most florid of all Rai smiths. His senior student in the Rai school, Rai Kunimitsu's influence should be taken into consideration, but nevertheless the ji and ha are pronouncedly more nie dominant. Presence of yubashiri as well as chikei allows him to remain in the clique.Dr. Honma Junji

Dr. Honma as seen above was positive on whether or not Kunitsugu could have been a student of Masamune, however Tanobe sensei believes that this theory doesn't hold true.

Detail of Juyo Rai Kunitsugu Katana

The top of the hi is lowered slightly. The hi is made wide and a little shallow. The hi is flawless.


The width of the hamon is wide and worked in nie with suguha choji midare and the whole of the hamon will be in notare. There is much life in the nie all along the blade and the work will be like those of the early Soshu smiths like Yukimitsu and Sadamune. There will be differences in the sizes of the nie and the color from it will be very strong.


Very finely worked steel results in ko-mokume hada with itame mixed in places. Also o-hada will show in places. Abundance of ji-nie will result in yubashiri and chikei. Yamanaka, Nihonto Newsletters

Detail of Juyo Rai Kunitsugu Katana

Seven of his blades were listed in the Kyoho Meibutsucho, and these include the Minamoto Rai Kunitsugu which takes its name from its mei and is now lost, the Torikai Rai Kunitsugu which was owned by the Owari Tokugawa and valued at 300 mai, the Akita Rai Kunitsugu, the Sansai Rai Kunitsugu the Togawa Rai Kunitsugu the Masuda Rai Kunitsugu and the Aoki Rai Kunitsugu which was owned by the Tokugawa Shoguns. This is more than any of the other Rai smiths and speaks to the regard in which he was held.

Rai Kunitsugu's dated work contains only one date, on a ken, which places him at 1327 though his earliest work is thought to come from around 1303. There are oshigata of two tanto with 1330 and 1332 dates in the Kozan Oshigata as well but these blades are lost now. This places Kunitsugu right at the end of the Kamakura period into the beginning of the Nanbokucho, so we see some transitional style in his work. His tanto tend to be larger and wider than those of Rai Kunitoshi and Rai Kunimitsu as a result, and this hyper masculine style makes his work stand out from the other Rai smiths. Some of his blades have extremely strong nie utsuri which can be shown in oshigata so that it looks like hitatsura. This is another Soshu like feature in the smith, as well as the muneyaki which accompanies some works.

Detail of Juyo Rai Kunitsugu Katana
Honami oshigata showing nie utsuri and Minamoto mei
Honami oshigata showing nie utsuri and Minamoto mei
Detail of Juyo Rai Kunitsugu Katana

These [Rai Kunitsugu] works are different than those of the other Rai smiths and are imbued with the KAMAKURA style. Tanto are plentiful, and tachi are few. The tachi sugata is Kyosori, the mihaba is wide, the iori is deep, and there are some in which the kissaki is elongated.

In tanto, there are ordinary types, and there are also some that are fairly sun-nobi. As for the hamon, there are some in which the itame is fairly hadatachi, the ji-nie is thick, there is yubashiri and tobiyaki, and there are also some that are mune yaki. In regard to the hamon, ko-midare and notare are the most common, rarely there is also suguba, and there is also occasionally one which has a large pattern midare.

The nioi and nie are deep (wide nie and nioi lines), there is ashi, and there are many in which the yakiba is wider and which are more gorgeous than those of RAI KUNIMITSU. The boshi is komaru, there are also some that are a bit togari (pointed), and there are also some that are midarekomi. For horimono, there are ken, bonji, gomabashi, hi and such, and generally these are larger than those of other smiths. The nakago mune is kaku, and the yasuri is kiri. Nihonto Koza

Detail of Juyo Rai Kunitsugu Katana

While the Rai school traditionally works in choji and suguba, Rai Kunitsugu departs from this and features notare in his repertoire. Of the Soshu smiths, his work most looks like Sadamune when it's in this style.

There is no doubt that Kunitsugu with his background in the Rai tradition was exposed to great influence of Masamune when he moved out to Kamakura. All his extant works evidence this change in his workmanship and styles.


Of the two tachi works which are considered most representative of his work, one is wide and has a stately shape. That is to say, the more manly type of shape of this tanto can be seen on his tachi works. NBTHK English Token Bijutsu

Detail of Juyo Rai Kunitsugu Katana

Kunitsugu was the one who innovated the pronouncedly nie-structured florid midare that no Rai artisans before him had produced. Rai Kunimitsu, his contemporary, did a similar style, but Kunitsugu's nie in both ji and ha are overwhelmingly powerful and form kinsuji, chikei and yubashiri. His ha is markedly wide on the whole.

This outstanding nie trait, the core of the Soshu tradition, is the very reason that includes him in the so-called Masamune Juttetsu. He has long been called Kamakura Rai. In Funkiron he is described: having become Masamune's student, he modified the Rai style and his kitae changed to itame. He was devoted to the Kamakura or Soshu style. NBTHK English Token Bijutsu

The following two charts show the blades accepted at Juyo and Tokuju by the NBTHK. The first chart shows clearly that Rai Kunimitsu is the most frequent attribution within the Rai school at 155 blades and 22% of the total. There are an additional 28 Tokuju. For Rai Kunitsugu the numbers are much smaller, with 30 blades at Juyo and 14 at Tokuju. This shows also a very high ratio of 1 out of 3 Rai Kunitsugu passing Tokuju. But you can see from the charts how rare the work is within the overall body of school work.

The second chart plots individual swords passing and compares against Juyo sessions. We can see trends building over time as the lines darken and cluster in terms of how things are attributed. In the last 10 years only 3 Rai Kunitsugu pop up. These visualizations are tools I use to understand relative rarity of these judgments and makers.

School Frequency
Pass by Volume

Rai Kunitsugu's work is much more rare than Rai Kunitoshi and Rai Kunimitsu, but is held in equally high regard. Because of this we see 41 Juyo Token, 15 Tokubetsu Juyo Token, 6 Juyo Bijutsuhin, 4 Juyo Bunkazai and one Kokuho blade made by him. Fujishiro ranks him at the top as Sai-jo saku. Of the NBTHK attributed blades, there are a total of 28 katana and 8 tachi, making daito by this smith very rare. Kunitsugu also carries a great reputation for functional blades as he is rated O-wazamono.

Detail of Juyo Rai Kunitsugu Katana
Juyo Token Rai Kunitsugu Katana

Juyo Token Rai Kunitsugu Katana

This outstanding blade has a premium length and a very wide mihaba, making for an imposing shape. I looked at all of the other NBTHK authenticated blades and this one was the widest along with one other of the same shape and happens to be a signed tachi. The pointed boshi and fine kitae point to Rai Kunimitsu and Rai Kunitsugu, but the blade has very strong ji nie, and a notare based hamon which is very similar to Sadamune. The ji nie form nie utsuri which is very bright and one of the major highlights of this blade, making it like a kaleidescope when you view it. All of this points directly at Rai Kunitsugu as the best attribution for this sword.

Rai Kunitsugu is the most difficult of the major Rai smiths to find for a collector. This is the first one I've been able to obtain and I've only seen them on a few occasions in the possession of high level collectors. The work has always been excellent.

Of Rai Kunitsugu's work, this one is the widest and most magnificent. The NBTHK wrote it up as kenzen meaning it is in a perfect state of health. Tanobe sensei referred to it as an energetic masterwork. In spite of this there is a little bit of Rai hada on the blade, but nothing major and it does not detract at all from its beauty.

Rai Kunitsugu is said to have made very clean and wide bohi and it points to a construction choice to get this result. This blade shows a particularly clean bohi and agrees with this kantei point, and Yamanaka's descriptions above sound like they are targeted at this blade.

There is also one kirikomi (a cut in the steel from a sword strike) that can be found on the blade as well, showing it went to battle.

I think this sword stands a good chance of passing Tokubetsu Juyo and Tanobe sensei encouraged me to submit it in the next shinsa. It is one of a handful of great pieces I was able to obtain during 2020, in which I spent almost the entire year in Japan due to the pandemic. It's a really great catch for someone trying to collect the Masamune Juttetsu as this smith is so hard to come by, and this example is particularly great and shows off the beginning of the transition into the massive swords of the Nanbokucho period.

Detail of Juyo Rai Kunitsugu Katana
Rai Kunitsugu Katana OshigataRai Kunitsugu Katana Origami

Juyo Token Katana

Appointed on the 8th of September, 1980 (Session 27)

Katana, Mumei, Den Rai Kunitsugu


shinogi-zukuri, iori-mune, wide mihaba, relatively shallow sori, ō-kissaki


dense ko-itame that features plenty of ji-nie and a nie-utsuri


ko-nie-laden chū-suguha-chō with a wide nioiguchi that tends to a gently undulating notare and that is mixed with gunome, ashi, fine sunagashi, and kinsuji


notare with a pointed and rather late starting kaeri


on both sides a bōhi that runs as kaki-tōshi through the tang


ō-suriage, kirijiri, kiri-yasurime, two mekugi-ana, mumei


It is said that Rai Kunitsugu (来国次) was the son of Rai Kunitoshi (来国俊) and that he was in a junior position to his brother Rai Kunimitsu (来国光). It is also said that he studied with Sōshū Masamune (正宗) later in his career as his style moves away to a certain extent from the traditional Rai style and incorporates a noticeable amount of Sōshū elements.

This blade has a wide mihaba and an elongated kissaki and is thus of the typical shape from the Nanbokuchō period. It shows a suguha-chō that tends to a gently undulating notare and that is mixed with gunome. Both ji and ha are nie-laden and plenty of hataraki like chikei and kinsuji appear. The jiba of this blade is perfectly healthy (kenzen) and is interpreted in one of Rai Kunitsugu’s known styles.

Rai Kunitsugu Katana Sayagaki


This sword bears an extensive inscription (sayagaki) by Tanobe Michihiro sensei. He is the retired former head researcher of the Nippon Bijutsu Token Hozon Kyokai (NBTHK). Joshu is the old name for Yamashiro province.

  1. 城刕来国次
    Joshu Rai Kunitsugu
  2. 第二十七回重要刀剣
    Dai nijūnana-kai jūyō-tōken
    Jūyō at the 27th jūyō shinsa
  3. 大磨上無銘也
    Ō-suriage mumei nari.
    This blade is shortened and unsigned
  4. 幅廣・重ネ厚デ大鋒トナル豪快勇渾ノ形状ヲ呈シ地沸ヲ厚ク敷キ地景入リ沸映ノ立ツ精強ナル小板目ノ肌合ニ浅ク湾心ノ直刃ヲ焼キ沸匂深厚ナリテ金筋絡ミ刃中沸足頻リニ働キ突上ゲテ尖ッて返ル迫力アル帽子ニ結ブナド来傳ノ品格ヲ基軸ニ更ニ沸ヲ強調シテ活氣ガ加味サレタル出来ヲ示シ同工ノ特色ヲ顕現スル貫録十分ノ優品也
    Haba-hiroku, kasane atsuku de ō-kissaki to naru gōkai yūkon no keijō o tei-shi ji-nie o atsuku shiki chikei hairi nie-utsuri no tatsu seikyō naru ko-itame no hada-ai ni asaku notare-gokoro no suguha o yaki nie-nioi shinkō narite kinsuji marami hachū nie-ashi shikiri ni hataraki tsukiagete togatte kaeru hakuryoku aru bōshi ni musubi nado Rai-den no hinkaku o kijiku ni sara ni nie o kyōchō-shite kakki ga kami-saretaru deki o shimeshi dōkō ni tokushoku o kengen-suru kanroku jūbun no yūhin nari.
    It is with its wide mihaba, thick kasane, and ō-kissaki of a powerful and magnificent shape. It shows a refined but prominent ko-itame that features plenty of ji-nie, chikei, and a nie-utsuri, is hardened in a nie-laden suguha that tends slightly to notare, that has a wide nioiguchi, and that is mixed with kinsuji interwoven into the forging structure and plenty of nie-ashi, and with the vivid bõshi with its late starting and pointed kaeri, we recognize that the jiba is based on the elegant style of Rai tradition. However, the nie are noticeably emphasized and the blade is also full of energy and so we have here a masterwork that truly reflects the characteristic features of Kunitsugu.
  5. 刃長弐尺参寸六分余有之
    Hachō ni-shaku san-sun roku-bu yo kore ari
    Blade length ~ 71.6 cm
  6. 于時令和弐季庚子霜月探山識「花押」
    Koretoki Reiwa ninen kanoe-ne shimotsuki Tanzan shirusu + kaō
    Written by Tanzan [Tanobe Michihiro] in November of Reiwa two (2020),
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