Tachi〈Inscribed by Kosaku Suminaga, Osafune, Bizen Province

A Tachi by Nagamitsu, Dated to the Year 1300

In the second month of Shōan 2, the year 1300 by the Western calendar, a swordsmith in the village of Osafune finished a long curved blade and cut two lines of characters into its tang. One line gave his name: Nagamitsu of Osafune, in the province of Bizen. The other gave the date. Dated works from this maker are not common, and the year stamped here places the sword among the later examples of his long career.

This tachi carries a second distinction, one that has nothing to do with its steel. According to the survey of designated objects carried out by Japan's Agency for Cultural Affairs, the blade is currently listed among Important Cultural Properties whose location is unknown. The standard reference compendium of national treasures and important cultural properties records the sword without a photograph of the blade itself. What follows, then, is an account of a documented object that visitors cannot stand in front of, and a guide to the closely related works of the same master that they can.

The Maker and the Osafune School

Nagamitsu worked in Bizen province, the stretch of country along the lower Yoshii River in what is now the southeastern part of Okayama Prefecture. The region had supplied swordsmiths since the Heian period, drawing on local sand iron of unusual quality. By the thirteenth century the workshops clustered at Osafune, a settlement in present-day Setouchi City, had risen to dominate the trade.

Nagamitsu was the son of Mitsutada, the smith generally credited with putting the Osafune school on its feet. He inherited his father's methods and pushed the workshop into its first period of real fame. Among collectors of old swords he is remembered for the sheer number of signed blades that survive under his name, more than almost any other smith of the classical era.

His range was wide. Some blades show the flamboyant, billowing clove-shaped temper line that his father favoured. Others, including this one, settle into something quieter. A point worth knowing for anyone who later examines his work: the shape of the tempered area at the very tip, the part Japanese connoisseurs call the bōshi, takes a distinctive turn in his blades. The same form recurs in the work of his son Kagemitsu and the smith Sanenaga, and the three are grouped together because of it.

A long-standing puzzle hangs over dated blades like this one. Older catalogues proposed that there were two smiths named Nagamitsu in succession, and assigned the dated pieces of the 1290s and 1300s to a second generation. More recent study leans the other way, treating the output as the work of a single man across roughly three decades. The question is unsettled, and a reader will find the sword discussed both ways depending on the source.

Why It Was Designated

The blade was registered as an Important Cultural Property on 29 March 1952. The case for it rests on three things that line up at once: a clear, legible signature; a firm date; and condition that has not been compromised by later reshaping.

The last point matters more than it sounds. Many old tachi were shortened over the centuries to suit changing fashions in how swords were worn, a process that erases the original tang and often the signature with it. This blade keeps its original tang, the file marks across it slanting gently downward in the manner expected of the school. A signed, dated, unaltered work by a first-rank Kamakura master is the kind of fixed point that scholars use to date and attribute the many unsigned blades around it. That evidential value, as much as the beauty of the steel, is what the designation recognises.

Reading the Blade

The sword measures 77.3 centimetres along the cutting edge, with a curvature of 2.6 centimetres. The curve sits low, near the hand, and the blade tapers in a way that reads as both elegant and built for use. The cross-section is the standard ridged form, with a peaked back.

The surface of the steel carries a wood-grain pattern, scattered with the fine bright particles and dark threading that come from careful folding and forging. Running faintly through the body is a misty reflection that old Bizen blades are known for, a kind of shadow in the metal that shifts as the light moves. The temper line is built in soft nioi, a hazy band rather than a sparkling one, holding small clove shapes against a near-straight base, with fine activity reaching into the edge.

Two carvings survive on the lower part of the blade. On the side worn outward sits a sankozuken, a straight ritual sword whose grip ends in a three-pronged thunderbolt, a motif drawn from esoteric Buddhism. On the reverse is a single bonji, a Sanskrit seed-syllable of the kind used as a compact stand-in for a deity. Carvings like these turned a weapon into something closer to a votive object, and they are part of why a sword of this period was treated as worth preserving across seven centuries.

Where to See Nagamitsu's Work

Because this particular blade cannot be viewed, the natural place to begin is the country where it was made. The Bizen Osafune Sword Museum stands in Setouchi City, on the ground where the school once worked. It is the only public museum in Japan devoted entirely to swords. Around forty blades are on show at any one time, with the displays rotating several times a year, and Bizen work is the heart of the collection. On the second Sunday of each month, smiths give a public forging demonstration, heating and hammering steel in the old way. Visiting workshops on the same site let you watch polishers, scabbard makers, and blade carvers at their benches.

For Nagamitsu specifically, the Tokyo National Museum holds two of his finest blades, shown in rotation rather than permanently: the celebrated Daihannya Nagamitsu, a national treasure that took its nickname from a valuation equal to the six-hundred-volume Great Wisdom Sutra, and a second tachi that descended through the Ikeda lords of Inaba. The Hayashibara Museum of Art in Okayama keeps a dated tachi of his from 1289, and the Sano Art Museum in Mishima, Shizuoka, holds a naginata blade bearing his signature. Display schedules change, so it is worth checking each museum's current exhibition before making a trip.