Tachi Sword (inscribed with Bishu Nagafune Kagemitsu / with

A Kamakura Sword Signed by Osafune Kagemitsu

The blade carries six characters cut into its tang: Bishū Osafune Kagemitsu. They name the smith who led the Osafune workshop in Bizen province, the stretch of the Yoshii River valley that today falls within Setouchi City in Okayama Prefecture. Kagemitsu worked through the closing decades of the Kamakura period (1185 to 1333), and dated examples of his work survive from 1306 to 1334. This particular tachi is held at the Tokyo National Museum in Ueno, and it comes paired with an itomaki-no-tachi koshirae, a formal cord-wrapped mounting that the designation treats as part of the object.

Kagemitsu sits third in the Osafune line. The school was founded by Mitsutada, passed to his son Nagamitsu, and then to Kagemitsu, who is recorded under the courtesy title Sahyōe-no-jō. His son Kanemitsu carried the forge into the following century. Across three generations the family turned Osafune into the most productive sword tradition of medieval Japan, and Kagemitsu is usually counted among its three defining hands alongside Nagamitsu and Sanenaga.

Why It Holds an Important Cultural Property Designation

Japan registered this sword as an Important Cultural Property on 29 August 1950, under designation number 01135. The category sits one step below National Treasure, and the distinction matters here because the same museum keeps a more famous Kagemitsu blade, the National Treasure known as Koryū Kagemitsu. The two are different swords by the same smith, and visitors sometimes conflate them. The piece described here is the signed tachi with the cord-wrapped tachi mounting, valued as an authenticated late-Kamakura Kagemitsu work that survives together with a complete formal set of fittings.

What gives the designation its weight is the combination of maker and condition. A securely signed Kagemitsu blade is already a reference point for the late phase of Bizen swordmaking. Add a matching itomaki-no-tachi mounting, the dress reserved for ceremonial and votive use, and the object records how such a sword was forged and, just as usefully, how it was meant to be worn and presented.

What to Look For

Three features mark Kagemitsu's hand, and each rewards a slow look through the display glass. The first is the steel itself. He forged a tight ko-itame grain, a small wood-like figure in the surface, and over it raised a midare-utsuri, a cloudy band of reflection that floats above the temper line like breath on cold glass. The clarity of this misty figure is one reason Osafune steel of this period is held in such regard.

The second is the temper line, or hamon. Kagemitsu often worked in a narrow straight line set with small clove-shaped ko-chōji, and he is closely tied to a pattern called kataochi-gunome, a row of half-collapsed humps that lean in one direction. The effect is disciplined rather than showy, quieter than the flamboyant clove patterns of his predecessors.

The third is the mounting. An itomaki-no-tachi koshirae wraps braided cord over the upper part of the hilt and again across the upper scabbard near the mouth. The wrapping is both grip and ornament, and it signals a sword dressed for formal occasions rather than the battlefield. Because the Cultural Affairs database does not publish the blade's measurements for this entry, the proportions are best judged in person against the gallery's labels.

Around the Museum

The Tokyo National Museum stands at the northern end of Ueno Park, a short walk from Ueno Station. Japanese swords are shown in the Honkan, the main gallery building, in a dedicated room on the ground floor where blades are lit to bring out the grain and temper line. Displays rotate every few months to protect the works and to keep the selection fresh, so any single sword moves on and off view.

Ueno Park itself repays a full day. The grounds hold several museums, a famous spread of cherry trees that draws crowds each spring, Shinobazu Pond with its lotus beds, and Kan'ei-ji and Tōshō-gū shrine among the older structures. If swords are your reason for the trip, time your visit to the museum's exhibition calendar, since the gallery's lineup is announced in advance.