Sword (inscribed Shinko)

The Tachi Signed "Sanemitsu": A Kamakura Blade That Outlived the Warlord Who Gave It Away

In the spring of 1582, the Takeda clan had just been destroyed at Mount Tenmoku, and Oda Nobunaga was making his way home through Mikawa Province. He stopped at Yoshida Castle, where a senior Tokugawa retainer named Sakai Tadatsugu had been put in charge of receiving him. Before leaving, Nobunaga handed Tadatsugu a long sword along with two hundred ryo of gold. Barely two months later Nobunaga was dead, ambushed at the Honnoji temple in Kyoto. The sword survived him by more than four centuries. It now sits in a museum in the far north of Japan, in the city of Tsuruoka, and its tang carries two characters cut into the steel: Sanemitsu.

This is a tachi, the older type of Japanese long sword, worn slung from the belt with the cutting edge facing down rather than thrust through the sash edge-up like the later katana. The blade dates to the Kamakura period (1185–1333), generations before Nobunaga ever held it. Its maker, Sanemitsu, is traditionally counted among the pupils of Nagamitsu, one of the great smiths of the Osafune school in Bizen Province, the region that produced more celebrated swordsmiths than anywhere else in medieval Japan. Few works bearing Sanemitsu's signature have come down to us, which is part of what makes this one matter.

Why It Is a National Treasure

The blade was first designated in 1935, under the system that governed cultural property before the Second World War. When Japan rebuilt that system with the Law for the Protection of Cultural Properties, the most significant items were re-examined and elevated again. This sword was named a National Treasure on 31 March 1953, the highest rank the country gives to a work of art or craft.

Two things lift it to that level. First is the quality of the blade itself. Sanemitsu's surviving output is thin, and among the pieces attributed to him this one is regarded as both the finest and the soundest, with no significant flaws or later shortening. Second is what came wrapped around it. The sword arrived from Nobunaga in a silk-corded tachi mounting, an itomaki no tachi koshirae, in the showy taste of the Momoyama age. That mounting has stayed with the blade ever since, and it carries the National Treasure designation alongside the steel. A blade and its original fittings surviving together, undisturbed, across four and a half centuries is genuinely rare.

The signature deserves a closer look. It reads simply "Sanemitsu," two characters cut at the center of the tang below where the collar sits. The lower character, mitsu, runs right up against one of the peg holes, a small detail that swordsmiths and appraisers use when judging authenticity.

The Sword and the Sengoku

To understand why Nobunaga gave the blade to this particular man, go back seven years. At the Battle of Nagashino in 1575, the combined Oda and Tokugawa armies broke the Takeda cavalry. Sakai Tadatsugu had proposed and then led a surprise attack on the Takeda fort at Tobigasuyama, hitting it from the rear and removing a threat that could have turned the main battle. It was the kind of decisive stroke commanders remember.

By 1582 the Takeda were finished. Their last leader, Takeda Katsuyori, took his own life at Mount Tenmoku as the Oda and Tokugawa forces closed in. Nobunaga, returning south, paused at Yoshida Castle in Mikawa, where Tadatsugu hosted him. The gift of the Sanemitsu blade and the gold was a reward for years of service, Nagashino chief among them.

Tadatsugu is remembered as the senior figure among the Tokugawa Shitenno, the four generals Ieyasu trusted most. He had stayed at Ieyasu's side since the future shogun's boyhood as a hostage. He died before the Tokugawa shogunate was founded, but his descendants prospered under it. The Sakai house was eventually installed as lords of the Shonai domain, entering Tsuruoka in 1622, and the sword traveled north with them. That is how a blade once handled by Nobunaga ended up in Yamagata, far from the central battlefields where its story began.

What to Look For

Stand in front of the blade and the first thing to register is its shape. It carries a high curve concentrated near the base, the koshizori profile typical of Kamakura work, and the body is broad and confident. The point, or kissaki, is the compact ikubi form, short and stout like a boar's neck, another hallmark of the period. These proportions read as old and strong even to an untrained eye.

Look along the surface and the temper line emerges. Sanemitsu set a choji pattern, the clove-shaped outline that the Bizen smiths made their signature, mixed with small rounded undulations called gunome. The line is deep in nioi, the soft misty band of hardened steel, and the side that would face inward when the sword was worn runs more flamboyantly than the outer face, with extra activity near the base. In the point the temper turns back in an irregular sweep ending in a slight peak, and bright streaks of kinsuji flash across the outer face. A single straight groove, the bohi, is cut down both sides of the blade and runs off toward the tang.

The blade is held at the Chido Museum in Tsuruoka, the institution founded by the Sakai family itself. It is not on permanent view, since the museum rotates its art exhibitions and a National Treasure blade is shown only on occasion, so anyone making the trip specifically to see it should check the current schedule first. The museum also holds a second National Treasure sword, a tachi signed Nobufusa that Ieyasu gave Tadatsugu two years after Nobunaga's gift, which means two swords presented to the same warrior by two of the three great unifiers of Japan now rest under one roof.

Around the Museum

The Chido Museum occupies the old residence grounds the Sakai lords kept on the third bailey of Tsuruoka Castle, and it is less a single gallery than a small compound. Several Meiji-era buildings have been moved here and preserved, among them the former Nishitagawa District Office and the former Tsuruoka Police Station, both pseudo-Western structures designated Important Cultural Properties, along with the thatched former Shibuya house. A book-style garden behind the lords' retirement villa, the Sakai Family Garden, is a nationally designated Place of Scenic Beauty, and the collection of folk implements from the Shonai region has been recognized as Important Tangible Folk Cultural Property. The compound earned a star in the Michelin Green Guide to Japan.

The site sits just west of Tsuruoka Park, which covers the grounds of the former castle, so a sword visit folds naturally into an afternoon of walking the old domain seat. Most visitors give the museum about an hour, though the spread of buildings rewards two.