A Kamakura Tachi Signed Nagamitsu
Two small characters cut near the top of the tang read Nagamitsu. They are easy to overlook, yet they connect this curved blade to one of the most accomplished swordsmiths Japan produced in the thirteenth century. The sword is a tachi, a long blade worn slung from the belt with its cutting edge turned downward, the form that came before the later katana. It was forged in Bizen province by the Osafune school, and Japan lists it as an Important Cultural Property.
Nagamitsu worked in what is now the southeastern corner of Okayama Prefecture, in a riverside district called Osafune on the Yoshii River. The area sat beside rich deposits of iron sand, and by the late Kamakura period its forges had overtaken older rivals to become the busiest center of swordmaking in the country. Nagamitsu was the son of Mitsutada, the smith regarded as the founder of the Osafune line. He is credited with setting the school on the footing that would keep it productive for the next three centuries.
The blade runs 70.2 centimeters along the edge, with a curvature of 2.7 centimeters. At some point in its long life it was shortened from the base, a common fate for old tachi as fashions in how swords were carried changed. Even after that work, it keeps the deep curve concentrated near the hilt that marks a genuinely early sword, along with a visible taper, or funbari, where the blade widens toward the tang.
Why the Blade Was Designated
Japan recognized this sword as an Important Cultural Property on June 28, 1956. The designation sits one tier below National Treasure status, which a handful of Nagamitsu's very finest blades hold, among them the famous Daihannya Nagamitsu in the Tokyo National Museum. Several of Nagamitsu's swords are National Treasures, and more than two dozen others, this one included, carry the Important Cultural Property rank.
The Agency for Cultural Affairs notes a particular reason this example matters. Signed works by Nagamitsu survive in fair numbers, since he was one of the most prolific smiths of the old-sword era. Blades that have come down to us in close to their original condition, however, are scarce. This tachi was shortened only slightly, so it preserves much of the shape and character Nagamitsu gave it, and its temper is described as a brilliant clove-pattern work.
That temper, the hamon, is the line of hardened steel running along the edge, formed when the smith coats the blade in clay and quenches it in water. On this sword the pattern is chōji, a row of forms shaped like clove buds, intermixed with rounded gunome undulations. Fine tempered streaks called ashi and yō reach into the edge, and the misty band that defines the line, the nioi, is deep and clear. A clove-pattern temper of this kind is the signature of the Bizen tradition, and Nagamitsu inherited it directly from his father.
Reading the Blade
Look first at the steel itself. Nagamitsu forged the body in a tight ko-itame grain, a fine wood-grain figure produced by folding and welding the metal many times. Above the edge floats a midare-utsuri, a faint cloud-like reflection that appears and fades as the light moves across the surface. This shadow is not decoration applied to the blade. It is a feature of the steel created during quenching, and a well-formed one is prized as evidence of a master's control over heat and timing.
The cross-section is shinogi-zukuri, the standard ridged profile, with a peaked iori-mune back and a medium point. Turn the sword toward the tip and the temper runs irregularly into the bōshi, the hardened zone at the point, ending in a small rounded turnback on one face and a slightly pointed return on the other.
The tang carries the two-character signature and two peg holes, a record of the different hilts the blade has been mounted in over the centuries. None of this can be appreciated from a photograph alone. A blade like this reveals its grain and its temper only under raking light, turned slowly by hand, which is part of why these swords are studied in person rather than simply read about.
Where to See Nagamitsu's Work
This particular tachi is privately owned and is not on public display, so a visit to see it is not possible. The good news for anyone drawn to Nagamitsu is that several of his blades hang in museums that welcome visitors.
The Tokyo National Museum holds the Daihannya Nagamitsu, a National Treasure named after the high price it once commanded, which was equated with the six hundred scrolls of the Great Wisdom Sutra. The blade passed through the hands of the Ashikaga shoguns, Oda Nobunaga, and Tokugawa Ieyasu before being granted to the Okudaira family. It is shown in rotation roughly once every one to three years, so checking the museum's current exhibition schedule before traveling is wise.
To understand where Nagamitsu came from, the Bizen Osafune Sword Museum in Setouchi City, Okayama, sits in the very district where he worked. The grounds include a working forge, and on one day each month visitors can watch smiths heat tamahagane steel to around 1,200 degrees and beat it into shape, the same craft Nagamitsu practiced more than seven hundred years ago. Other Osafune blades by his hand are held at the Hayashibara Museum in Okayama and the Tokugawa Art Museum in Aichi.
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Q&A
- Can I see this sword in person?
- No. This tachi is held by a private owner in Tokyo and is not on public display. If you would like to see swords by the same smith, several are kept in public museums, which are described above.
- Where can I see a sword by Nagamitsu?
- The Tokyo National Museum owns the Daihannya Nagamitsu, a National Treasure shown periodically. The Bizen Osafune Sword Museum in Okayama, the Hayashibara Museum, and the Tokugawa Art Museum in Aichi also hold his blades. Exhibition schedules change, so confirm before visiting.
- What is the difference between a tachi and a katana?
- A tachi is the older form, worn hung from the belt with the edge down, and tends to have a deeper curve set near the hilt. The katana, which came later, was worn thrust through the sash with the edge up. This blade is a tachi from the Kamakura period.
- Why was the blade shortened?
- Shortening, called suriage, was done to many old tachi when the way swords were worn changed or when an owner wanted a different length. Metal was removed from the base, near the tang, rather than the tip. This blade was shortened only a little, so much of its original form remains.
- What should I look for in a Bizen Osafune blade?
- The clove-shaped chōji temper pattern along the edge is the school's hallmark, and so is the misty utsuri reflection in the steel above it. Both are best seen under angled light with the blade turned slowly, which is how swords are traditionally examined.
Basic Information
| Official name | Tachi, signed Nagamitsu (太刀〈銘長光〉) |
|---|---|
| Category | Craft, sword |
| Maker | Nagamitsu, Osafune school, Bizen province |
| Period | Kamakura period (13th century) |
| Designation | Important Cultural Property |
| Date designated | June 28, 1956 |
| Count | 1 blade |
| Dimensions | Edge length 70.2 cm, curvature 2.7 cm, width at base 2.9 cm, width at tip 2.1 cm |
| Location | Tokyo (privately owned) |
| Public access | Not on public display |
References
- Agency for Cultural Affairs, National Cultural Properties Database (Tachi, signed Nagamitsu)
- https://kunishitei.bunka.go.jp/bsys/maindetails/201/6569
- e-Kokuho, National Institutes for Cultural Heritage (Tachi, signed Nagamitsu / Daihannya Nagamitsu)
- https://emuseum.nich.go.jp/detail?content_base_id=100184
- Bizen Osafune Sword Museum, Setouchi City
- https://www.city.setouchi.lg.jp/site/token/
- WANDER Kokuho, Tachi signed Nagamitsu
- https://wanderkokuho.com/201-00457/
Last verified: 2026.06.17