Ryujin Swords

Katana attributed to ko-Naminohira NBTHK Hozon

Click on any picture for more detail.


Period: Hiean-early Kamakura.

Mei: Mumei.

Horimon: Suken with bonji (Sanskrit character) on one side, with a koshi-bi and bonji on the other. The suken represents Fudo-myoo, and was a very popular horimono in the Koto period.

Sugata: Shinogi-zukuri, koshi-zori, iori-mune.

Overall length: 38.70 inches (983.00 mm)

Nagasa: 29.29 inches (744.00 mm) long.

Nakago: Ubu, 9.41 inches (239.00 mm), two mekugi-ana. The yasurime are in most places non-existent - unsurprising in a blade this old - but there may be a hint of katte-sagari.

Kissaki: Ko-kissaki, 0.93 inches (23.5 mm). The boshi is o-maru.

Moto-haba: 1.14 inches (29.00 mm). Moto-gasane: 0.28 inches (7.00 mm). Saki-haba: 0.65 inches (16.50 mm). Saki-gasane: 0.16 inches (4.00 mm).

Sori: 0.79 inches (20.00 mm)

Hamon: Narrow suguha with nie.

Hada: Itame.

Blade condition:

In recent polish, and in excellent condition for its age. Some tiredness is just starting to show but after 800 years this is not surprising, and it is not a fault in Koto swords. The blade has a cut mark from another sword near the shinogi. There is a second, almost invisible, nick on the mune - it's more of a catch really - so it was obviously in at least one fight.


In Edo period koshirae. There are only two mekugi-ana, and the tsuka fits the second one perfectly, so it is original to the sword.

The fuchi-kashira have a simple nanako design and are possibly of shakudo. The menuki are of shakudo, gold and silver; they depict two people hauling a boat containing some sort of cargo from the waves. The habaki was originally gold-washed, but most of that has rubbed off over time. The lacquering of the saya is of a stripy pattern seen in Satsuma. This is unsurprising, given that the sword itself is from a Satsuma school. The saya is rather battered, but could be restored. One seppa is from a shingunto, the other may be original. There is some play in the fittings between the fuchi-kashira and the habaki, but nothing that the correct seppa won't fix.

The iron tsuba has a number of brass dots around a central star-shaped design that surrounds the nakago-ana. One brass pin is missing, and another is tarnished. The tsuba doesn’t, on the face of it, seem to be a terribly interesting design until you look at it very closely. Only one of the brass pins goes through the thickness of the tsuba, and although the pattern appears at first glance to be identical on both sides, it isn't. Obviously there had to be a rationale for this based on the customer’s requirements. Presumably the tsuba-shi’s efforts satisfied those requirements, because the customer put the tsuba on their sword.

The tsuba isn’t interestingly artistic because it is functional. It is a sidereal wind rose. Wind roses preceded the compass rose, and were used on maps to indicate the direction from which the eight principal winds blew. No differentiation was made between the cardinal directions, and the winds that blew from those directions. The Japanese learnt of wind roses from the Portugese portolans, and used them when they started drawing their own portolans. A sidereal wind rose is a refinement of this; it indicates the direction from which the eight principal winds blow by the navigational stars appropriate to those directions.

Identifying navigation stars can be very difficult. With most Chinese texts you only have the measured angle up from the horizon (declination) of a single star at the time of observation. Problems arise because you don’t usually have the time of observation or even the season, the name may be peculiar to navigational usage, asterisms are for solely navigational convenience and may not follow any astronomical norms, the destination may yet to be identified, and the degree of error is often unknown. Other than that it is, to use a pun, plain sailing.

Things are easier in this case, since some of the information is already given. On both sides of the tsuba there is a line of three stars, the brass pin representing the central star being bigger. This is the only pin to go entirely through the tsuba. The design represents Orion’s belt, known to the Japanese as Mitsu Boshi. This group of stars had an important role in Japanese agriculture during the feudal period; it determined planting and harvesting times, hence their other names of Komeinya boshi (rice stars) and Awaine boshi (millet stars) (Renshaw 1999). They were also called Sumiyoshi boshi by Japanese fishermen and sailors, the Sumiyoshi being three deities created from the ocean, and thus were especially favourable towards seafarers (Nojiri 1988).

From left to right the three stars of the Mitsu boshi are Alnitak (Zeta Orionis and 50 Orionis), Alnilam (Epsilon Orionis), and Mintaka (Delta Orionis). The three stars see-saw about Alnilam with the seasons as they move across the sky. When Alnitak is lower, which happens September/October, it is time to harvest rice and plant millet (Renshaw 1999). When Mintaka is lower, which occurs April/May, it is time to plant rice and harvest millet. Coincidentally, the period after the rice harvest was favourable for catching the winds from the north-east to sail south and south-west, whilst early summer was the time for making the return journey. Historical records show that the outward bound voyages started before Christmas.

The three stars are shown in their setting positions; the western side of a sidereal wind rose is the setting side, since stars rise in the east and set in the west. The Mitsu boshi rise vertically at very nearly true east but set at an angle to the horizon at very nearly true West. Unsurprisingly, the Mitsu boshi on one side are in their winter configuration on one side, and in the late spring/early summer configuration on the other. They therefore conform to the known sailing seasons. This panel thus indicates both the start of the sailing season, and west.

Since we know that the Mitsu boshi represent the western setting point, we know that the second panel going clockwise is north. The stars represented here are Kochab (Beta Ursae Minoris) and Polaris (Alpha Ursae Minoris). Kochab moves around Polaris like the hand of a clock, and in fact European mariners used a device called a Nocturnal to tell the local time at sea based on this relationship. In this case, if Kochab is in the relationship shown on the tsuba, the necessary guiding stars for the voyage will be visible in their correct positions. Time is very important in navigation. In the absence of the yet-to-be-invented chronometer (which only became universal in 1900) and UTC this was an effective system if you were not too close to the equator.

Since the tsuba gives the sailing season (as indicated by the Mitsu boshi), and the approximate time for observations (as set by Kochab and Polaris), the remaining navigational stars can, given the right latitude, be identified by astronomical software and a nautical almanac. I have checked these positions back to the early 17th century.

Whilst most of the stars in the first picture are a fit for winter in the latitude of Nagasaki, the southernmost star, Achenar (Alpha Eridani) only appears briefly on the horizon at that latitude. You’re only likely to see it in a flat calm, which is no use for a sailing vessel. The latitude of Okinawa is, however, a perfect fit, which implies that the ship would put to sea during the day, sail south towards Okinawa, then correct its course that night based on celestial observations. Achenar becomes a significant navigational star at that latitude.

This means that the vessel would have to be going considerably further than the Ryukyu Islands. The only voyages in feudal Japanese history that would fit this description would be the 17th century Red Seal ships (shuinsen), which sailed in winter from Nagasaki for ports in the South China Sea. Until Japan was sealed, these large, armed merchantmen – many a hybrid of Asian and European shipbuilding techniques – carrying several hundred tons of very valuable cargo (silver bullion was exchanged for silks and other commodities), regularly travelled between Nagasaki and all the countries around the South China Sea and the Gulf of Thailand, plus going up the Straits of Malacca or round, via Selat Karimata, into the Java Sea to Ambon. The sole exception to the countries visited was China; China had forbidden Japanese ships to come into its ports as a reprisal for the activities of Japanese pirates.

This brings us to the other side of the tsuba, with the Mitsu boshi showing a sailing season of late spring. The star chart fits the latitude of Manila. It will not however be of use as far south as Batavia (modern Jakarta), because the horizon interferes with the Kochab-Polaris clock. Not that this would have presented a problem in the South China Sea; having reached the area, the navigator could use landmarks and the sun to navigate around the coast to Jakarta.

The pilot would use a backstaff (transmitted by the Portugese) to measure the angle between Polaris and the horizon. This angle is roughly the same as the latitude, although in China and Japan angles were expressed in fingers and quarter fingers, rather than degrees; one finger is 2 degrees. This is illustrated by the sailing instructions for Hormuz from the reign of the Ming emperor, Yongle (1402-1424):

“Fingers for crossing the ocean. Watch the North Star. At fourteen fingers there is Teng Ku Star, four and a half fingers in the east can be seen the Pleiades, with seven fingers and the thumb the Pu-Ssu Star may be seen in the south-west. Then with eleven fingers one may reach Ting-te-pa hsi. Sailing from there to Hormuz, watch for the North Star with fourteen fingers.” (Jung-Pang 2012, 110)

Similar records exist for other destinations. Chinese navigators checked their positions by measuring the altitude of at least four different stars that were close to the horizon (Shen-Lan 1433, 335). Japanese pilots would have done the same, and this tsuba provides the information to do that. During the day the backstaff could be used to check position by measuring the sun’s altitude at noon.

Although the backstaff is long gone, star charts are used for celestial navigation even today, despite GPS, as a modern chart for Falmouth shows on the left. These days you can get software that will display the stars that you need for the voyage, and their locations in the sky. After that, you take positional observations using a sextant, use degrees instead of fingers, refer to the ship’s chronometer for the time at the prime meridian in Greenwich, look up various tables, and do some calculations to get your latitude and longitude. The most notable difference - apart from the medium - is that the tsuba bases its 45 degree divisions of the sky on the old wind rose system, whilst the modern star charts use a 30 degree division derived from astronomy. Apart from that the basic principles, and the principal stars, haven’t changed, although the technology has.


The ko-Naminohira school was founded by Masakuni when, in the later Heian period (Eien; 987 AD), he moved from Yamato to Naminohira in Satsuma. The workmanship of ko-Naminohira blades is quite close to the workmanship of Yamato blades.

The blade is about 800 years old, and in surprisingly good condition for its age. Koto swords with ubu nakago are as rare as hen's teeth; pretty much all the other ko-Naminohira blades I've seen have been suriage, the exception being a tachi. This sword could go much further than Hozon papers. I wouldn't be in the least bit surprised if one day it recieved Juyo papers.

Naminohira blades were popular with Japanese seamen, because the characters could be alternately read as ""smooth waves, safe travelling". There was as a result a belief that you could be confident when travelling by sea if you had a Naminohira sword with you on a voyage.

The tsuba appears to be unique. I have enquired of collectors and craftsmen; none have ever heard of a tsuba like this. This should not be surprising; the number of pilots would always have been small. Although there were 350 licenced Red Seal ships there were only ten voyages a year, and only one navigator per ship.

Taking the sword and koshirae as a whole, the evidence points to this being the sword of a 17th century navigator of a Red Seal ship in its original koshirae. The indications of a Satsuma origin is not surprising; Satsuma relied heavily on maritime trade, and the Shimazu had earlier had a history of patronising piracy and smuggling (Lidin 2002, 58). The blade and its koshirae should never be split; this is far too valuable an historical artefact. Quite frankly, this sword probably belongs in a museum.

The Red Seal system started under Hideyoshi, but was formalised under Tokugawa Ieyasu, with major input from Will Adams, who helped build the first hybrid ships. The majority of permits were held by high ranking samurai families, or by merchants with samurai origins (or who were full samurai themselves). A few were held by favoured foreigners, such as Will Adams. Crews could be multinational, or they might be all Japanese. Japanese crew members might be samurai retainers, samurai looking for adventures in foreign parts, young men looking to get rich, outright adventurers and, for all anyone knows, people escaping trouble in Japan. One person involved in the Red Seal trade, Yamada Nagamasa, settled in what is now Thailand, became a privateer (a legal pirate), had his own 18 gun warships (2 cannon firing forwards), and wound up as governor of part of Siam with his own army. Another, Tenjiku Tokubei, went off exploring, travelled to India and the headwaters of the Ganges, and according to popular tales came back richer than most daimyo. There were no doubt many others whose adventures were not recorded.

The two nicks from sword fights fit in with what is known of maritime trade generally during this period, and the Red Seal crews in particular. Piracy and smuggling were endemic in the region during this period, and long after it. For example, the Dutch East India Company habitually raided the annual Portugese trading fleet on its way to Japan, and silk smuggling was a perennial problem at Macau, as the Portugese Jesuit Manoel Diaz reported in April 1610 (Cooper 2005, 57). However, the Red Seal crews seem to have been considered a particularly dangerous bunch by foreign port authorities, and their antics were at times more 'Pirates of the Caribbean' than merchants. According to one contemporary, Sir Edward Michelbourne:

“The Japons are not suffered to land in any port in India (Asia) with weapons; being accounted a people so desperate and daring, that they are feared in all places where they come.” (Boxer 1951, 268)

Whilst in 1615 a Dutch commander wrote that "they are a rough and a fearless people, lambs in their own country, but well-nigh devils outside of it". (Lidin 2002, 57)

In 1608 the crew of a Red Seal ship owned by the Hinoe daimyo Arima Harunobu, and crewed by Arima clan samurai, caused a diplomatic incident in Macau when, after several days of intimidating the local population, they initiated a mass brawl with Portugese soldiers using muskets and katana. They subsequently injured a Portugese magistrate who intervened, and killed his retainers. It required the intervention of the acting governor, Captain-major André Pessoa, and the local garrison to restore order. This resulted in the deaths of fifty of the samurai. The fifty surviving crew members were only released after they signed an affidavit saying that it was all their fault (Boxer 1951, 271). The shogun was not pleased, and in July 1609 he issued an edict forbidding Red Seal ships from calling at Macau (Boxer, 1951, 272). Any Japanese sailors that did reach Macau were, Ieyasu said, subject to Portugese law.

The events in Macau led, in 1610, to the Nossa Senhora da Graça incident in Nagasaki bay when Pessoa's ship - a carrack of over 1,000 tons - was attacked by large numbers of Arima clan samurai who were after revenge for Macau, and the huge cargo of silks (Boxer 1951, 270-85). After four days of attacks, now facing 3,000 samurai, with the ship boarded, the deck and mizzen sail on fire, and the crew overwhelmed, Pessoa set fire to the powder magazine. There were two huge explosions which destroyed the ship, the cargo, all the samurai who were either on board or in the vicinity, the attacking fleet of Arima ships, and those of the crew who were still living. The Arima lost large numbers of samurai and ships, and the cargo was never recovered. Almost immediately afterwards an apparently unrelated investigation by Tokugawa Ieyasu implicated Arima Haronobu in a conspiracy to assassinate the bugyo of Nagasaki. Although St Alphonsus de Liguori considered these to be trumped up charges, Harunobu was stripped of his lands, exiled to Kai province, and ordered to commit suicide (Liguori 345-346). Harunobu's son married Tokugawa Ieyasu's adopted daughter almost immediately after his father's death, and thus received the lands confiscated from his father.

This went a long way to smoothing over the monumental diplomatic mess created by the Nossa Senhora da Graça incident. Since everyone was anxious to resume trade, and since both principals in the incident were now dead, everyone could take the position that either Pessoa should have surrendered, or that Haronobu had overstepped his authority for personal reasons. The dead weren’t in a position to disagree. Furthermore, Haronobu’s death meant that all could avoid the embarrassing fact that Tokugawa Ieyasu, operating under the erroneous belief that he could do without the Portugese, had personally ordered Harunobu to arrest Pessoa at all costs – or kill him when he resisted arrest – in order to provide a legal fig leaf for seizing the ship and its cargo. Finally, the Arima clan was now in safe hands, and related by marriage to the Tokugawas, which meant that the shogun had even greater control over Nagasaki.

Not surprisingly, Manoel Diaz’ report on trade between Macau and Japan is deafeningly silent about the Nossa Senhora da Graça incident, even though news of the disaster had reached Macau by then. Even so, it still took two years of negotiation before Portugese merchantmen visited Nagasaki again.

The Red Seal system underwent later reform when it emerged that various daimyo were using Red Seal ships for large scale smuggling. From the Tokugawa's point of view, such smuggling meant that there was a risk of the daimyo building up their wealth and military power to the point where they could challenge the bakufu. Eventually the system ended when, in 1639, Tokugawa Iemitsu brought in the isolationist sakoku policy. Japanese sailors didn't venture as far afield again for nearly 300 years.

Offers accepted. Free shipping, bag included. Email me for payment methods. Currency conversion.


Boxer C R (1951), The Christian Century in Japan: 1549-1650, University of California Press.

Cooper M (2005), The Mechanics of the Macao-Nagasaki Silk Trade, in Ma D, Textiles in the Pacific 1500-1900, pp52-61, Burlington, VT.

Lidin O G (2002), Tanegashima: The Arrival of Europe in Japan, Nordic Institute of Asian Studies.

Liguori, Saint Alphonsus de, Victories of the martyrs; or, The lives of the most celebrated martyrs of the Church, ed. E Grimm (1954), Redemptorist Fathers.

Lo Jung-Pang (2012), Ed. B A Elleman, China as a Sea Power 1127-1368, A Preliminary Survey of the Maritime Expansion and Naval Exploits of the Chinese People During the Southern Song and Yuan Periods, Singapore.

Nojiri H (1988), Hoshi no Shinwa Densetsu Shusei (Collection of Mythology and Star Legends), Tokyo (in Japanese).

Renshaw Dr S and S Ihara (October 1999), Yowatashi Boshi; Stars that Pass in the Night: Japan's Cultural Heritage Reflected in the Star Lore of Orion.

Starr M (20 July 2015), Mysterious ancient star chart shows foreign skies., .

Ying-Yai Sheng-Lan (1433), The Overall Survey of the Ocean's Shores ed Huan Ma, Chengjun Feng (1970), Cambridge University Press.