Tachi (inscribed Masatsune)

An Introduction to the Blade

The sword measures 78.2 cm in blade length, with a deep curvature of 3.0 cm rising near the hilt. Its form—slender at the tip, robust at the base, with a pronounced "waist curve" (koshi-zori)—reflects the aesthetic ideals of the late Heian and early Kamakura eras, when tachi were worn suspended edge-down from the belt by mounted warriors. Alongside the blade itself, the silk-wrapped mounting (itomaki-tachi koshirae) decorated with chrysanthemum crests has been officially included in the National Treasure designation.

The sword is housed at the Kamakura Museum of National Treasures (Kamakura Kokuhokan), located within the grounds of Tsurugaoka Hachimangu, where it appears in special exhibitions every few years.

The Senoo Lineage

Within Ko-Aoe, two principal lineages existed. One, centered in the village of Aoe itself, used names containing the character "次" (tsugu)—smiths such as Moritsugu, Sadatsugu, and Tsunetsugu. The other was based in nearby Senoo (in present-day Minami Ward, Okayama City) and traced its origin to a smith named Noritaka. Masatsune was among the leading figures of this Senoo lineage.

Old records note that several swordsmiths used the Masatsune signature across different eras, and historians now believe more than one smith shared the name. The Masatsune of Ko-Aoe, however, is considered to have been active in the late Heian to early Kamakura period, roughly around the Yowa era (1181–1182) according to traditional swordsmith genealogies.

From the Imperial Court to the Tokugawa Shogun

This particular sword is said to have once belonged to the Imperial Court in Kyoto before eventually coming into the possession of the Tokugawa family. In the first year of the Genbun era (1736), the eighth shogun, Tokugawa Yoshimune, undertook a major restoration of Tsurugaoka Hachimangu. On the 15th day of the ninth month, the main transfer ceremony (shōsengū) was held, and two days later, the shogun's proxy, Toda Echizen-no-kami Tadayo, paid a formal visit to the shrine and presented this tachi as a votive offering. For the Tokugawa, who revered the shrine as the spiritual heart of their samurai heritage, offering a blade of this caliber was an act of profound devotion.

A Benchmark of the Ko-Aoe Style

Specialists note that this tachi embodies every hallmark of Masatsune's craftsmanship in its highest expression. The blade's shape preserves the graceful, upright bearing of a classical tachi of its era. The surface steel (jigane) shows the fine, undulating pattern called chirimen-hada—"crepe skin"—a characteristic feature of Ko-Aoe work, where small itame and mokume wood-grain patterns mingle to produce a shimmering, almost silken texture. Fine particles of jinie sparkle across the surface, and dark lines called chikei weave through the grain, giving the steel remarkable depth.

The tempered edge pattern (hamon) is a quiet but lively ko-midare, a small irregular wave of crystalline martensite produced in the nie style favored by the smith. The signature "正恒" is cut on the omote side of the tang, following the school's convention. In the words of the official record, the sword "preserves every feature of Ko-Aoe Masatsune, with a beautiful form and workmanship of the highest order."

The Accompanying Mounting

Also included in the National Treasure designation is the itomaki-tachi koshirae that accompanies the blade. This silk-corded mounting, with metal fittings of shakudō decorated in high-relief chrysanthemum crests and a scabbard finished in gold nashiji lacquer with maki-e chrysanthemums, is said to predate the Genroku era (1688–1704). The imperial chrysanthemum motifs support the tradition that the sword was once held in the imperial treasury before passing to the Tokugawa.

The Living Surface of the Steel

Under careful lighting, the chirimen-hada grain comes alive. Viewers can trace the faint cloudy patterns called utsuri that rise above the ridge line, one of the most admired qualities in early Japanese swords. The effect is impossible to photograph faithfully; it must be seen directly.

The Curve That Tells a Story

The pronounced koshi-zori—the curvature concentrated near the hilt rather than the tip—dates the sword to the age of mounted combat, when a curved blade could be drawn and swung in a single fluid motion from horseback. Visitors familiar with later swords will notice how different this archaic silhouette feels from the more balanced Kamakura-period shapes that followed.

The Mounting

The accompanying koshirae, though exhibited separately from the blade, is itself a masterwork of Edo-period metalwork and lacquer. The repeating chrysanthemum motif links the sword to its imperial past, while the precise finish of the fittings speaks to the wealth and ceremony of the eighteenth-century Tokugawa court.

Access

From JR Kamakura Station (accessible by the Yokosuka Line or Shonan-Shinjuku Line from central Tokyo) or from Enoden Kamakura Station, the shrine is roughly a ten-minute walk up the lively Komachi-dori shopping street. The Kamakura Museum of National Treasures stands near the east torii gate within the shrine grounds.

When the Sword Is on View

Because of conservation considerations, the tachi is not on permanent display. It appears in rotating special exhibitions every few years. Checking the museum's website before your visit is strongly recommended. Even when the sword itself is not shown, the museum's ongoing displays of Buddhist sculpture and sacred objects from the temples of Kamakura are richly rewarding.