A National Treasure Tachi by Osafune Chikakage: A Masterwork from the Late Kamakura Period

Among Japan's most treasured cultural properties is a magnificent tachi (long sword) bearing the inscription "Bizen no Kuni Osafune Ju Chikakage / Karyaku Ni-ni-nen □ Gatsu Hi" (備前国長船住近景／嘉暦二二年□月日). Forged in 1329 during the waning years of the Kamakura period, this blade stands as a testament to the extraordinary skill of its maker, Chikakage, one of the distinguished swordsmiths of the renowned Osafune school in Bizen Province (present-day Okayama Prefecture). Designated as a National Treasure of Japan, this tachi is recognized as one of the finest surviving examples of late Kamakura swordsmithing and a proud symbol of the Bizen sword tradition that dominated Japanese sword production for centuries.

The Swordsmith Chikakage and the Osafune Legacy

Osafune Chikakage (長船近景) was active from the late Kamakura period through the early Nanbokucho period, with dated works spanning from the Bunpo era (1317–1319) to the Teiwa era (1342–1345). He is believed to have been either the son of Chikatsune or a student of the great master Nagamitsu, who was one of the founding pillars of the Osafune school. Chikakage was a close contemporary of the legendary Kagemitsu, and the two smiths maintained a remarkably close working relationship — so much so that Chikakage is known to have signed certain blades on Kagemitsu's behalf using a distinctive reverse-chiseling technique known as saka-tagane.

The Osafune school itself was established in what is now Setouchi City, Okayama Prefecture, along the banks of the Yoshii River. Blessed with abundant supplies of high-quality iron sand from the Chugoku Mountains, the region became Japan's preeminent sword-producing center. The school's lineage runs from the founder Mitsutada through Nagamitsu, then to Kagemitsu and his son Kanemitsu, with Chikakage representing an important branch of this illustrious tradition. Together with Nagamitsu, Sanenaga, and Kagemitsu — collectively known as the "Three Masters of Osafune" (長船三作) — these smiths perfected the art of the boshi (temper pattern at the sword's tip), a technique of extraordinary difficulty that remains one of the hallmarks of the Osafune tradition.

Why This Tachi Was Designated a National Treasure

This tachi earned its designation as a National Treasure — the highest category of cultural property protection in Japan — for several compelling reasons. With a blade length of approximately 80.6 cm and a curvature (sori) of 2.8 cm, the sword preserves the dignified and graceful proportions characteristic of the late Kamakura period. The blade is rendered in the classic shinogi-zukuri form with iori-mune, exhibiting the elegant tachi silhouette favored by the warrior aristocracy of the era.

The ji-hada (surface grain of the steel) displays the Osafune school's characteristic ko-itame (fine wood-grain pattern) intermixed with mokume (burl-grain pattern), with vivid midare-utsuri (irregular reflection patterns) visible across the surface. The hamon (temper line) is executed in a primarily suguha (straight) style with subtle intermixtures of ko-gunome and ko-choji, demonstrating the quiet refinement and technical precision for which Chikakage was celebrated. The nioi-guchi (boundary of the temper line) is bright and well-defined, exhibiting the masterful heat treatment that only the most skilled smiths could achieve.

Crucially, this blade retains its ubu (original, unshortened) tang with the complete inscription and date, providing invaluable documentary evidence of its authorship and the precise year of creation. Many swords from this period have been shortened over the centuries to convert them from tachi to katana, making original-condition examples exceedingly rare and historically significant.

Highlights and Points of Appreciation

For enthusiasts of Japanese swords, this tachi offers a wealth of detail to appreciate. One of Chikakage's distinctive characteristics is the saka (backward-slanting) quality of his choji patterns — an important identification point that distinguishes his work from that of other Osafune smiths. His boshi, while similar to the famous san-saku boshi shared by Nagamitsu, Sanenaga, and Kagemitsu, crosses the yokote in a distinctive straight line before undulating slightly into a ko-maru shape.

The inscription itself is noteworthy. The date "嘉暦二二年" uses the old convention where "二二" represents "四" (four), indicating the fourth year of the Karyaku era (1329). The "□" in the date indicates that the month character has become illegible over the nearly seven centuries since the blade was forged. This kind of historical wear adds to the sword's authenticity and charm.

Chikakage is also famous for having forged the sword known as "Akechi Chikakage" (明智近景), which was treasured by the warlord Akechi Mitsuhide, the retainer who famously turned against Oda Nobunaga at the Honno-ji Incident of 1582. While that is a separate blade, the association underscores Chikakage's enduring reputation among Japan's warrior class across the centuries.

The Art of Japanese Swordsmithing: Understanding Bizen Tradition

To fully appreciate this National Treasure, it helps to understand the Bizen tradition (備前伝) — one of the five great swordmaking traditions (Gokaden) of Japan. Bizen Province was Japan's largest and most prolific sword-producing region, and approximately half of all swords designated as National Treasures or Important Cultural Properties are of Bizen origin.

The Bizen tradition is characterized by its use of nioi-deki (temper patterns formed primarily by fine particles), vivid utsuri (reflection patterns in the steel), and a warm, refined quality to the ji-hada. Bizen smiths worked with tamahagane (jewel steel) smelted from local iron sand, and the region's unique combination of raw materials, water, and climate contributed to the distinctive qualities of Bizen blades.

The late Kamakura period, when this tachi was forged, marked a time of both political upheaval and artistic refinement. After repelling the Mongol invasions of 1274 and 1281, Japanese swordsmiths developed broader, more robust blades. Yet by the 1320s, the so-called "unchangeable smiths" including the Osafune masters continued to produce elegant blades in the classical style — swords of dignity and restrained beauty that were especially prized by the Kyoto court.

Visiting Related Sites: The World of Japanese Swords

As this National Treasure is held in a private collection in Osaka Prefecture, it is not regularly available for public viewing. However, visitors interested in Japanese sword culture can explore several outstanding destinations to deepen their appreciation.