Great Sword <Kazuzo>

A Straight Sword Built Like the Curved Blades to Come

Held in private hands in Fukushima Prefecture is a single sword that records one of the quiet turning points in the history of Japanese arms. It is a chokutō, a straight sword of the kind carried in Japan from antiquity into the early medieval centuries, yet it is forged in a way that belongs to the curved swords that would eventually replace it. Dated to the Heian period (794 to 1185), it was recognized as an Important Cultural Property in 1989. The blade carries no maker's signature, and the national register lists no measurements for it. That is fitting for an object whose interest lies less in who made it than in what it shows about how the Japanese sword was changing.

For most of its early life the Japanese blade was straight. The deep curve the world now associates with the samurai sword arrived slowly, over generations, and this piece was forged while that shift was underway.

Why It Was Named an Important Cultural Property

The feature that settled its standing is the placement of the shinogi, the longitudinal ridge that runs the length of a blade. On most ancient straight swords the ridge sits close to the cutting edge, in a construction called kiriha-zukuri, with the steel falling away at a sharp angle from a high line near the edge. On this blade the ridge runs roughly down the center, the construction known as shinogi-zukuri. That central ridge is the form the mature Japanese sword would adopt and keep for the next thousand years. Finding it on a straight blade, rather than a curved one, is what makes the piece unusual.

The official appraisal places the sword in the process of change toward the Japanese swords of the mid-Heian period and later. Specialists compared it with the blades preserved in the Shōsōin, the eighth-century imperial repository at Tōdai-ji in Nara. Four swords of this general type survive there, and one resembles this blade closely, including the way the join between blade and tang is cut as a single clean line. Set beside those, this sword reads as a later step in the same lineage, carrying older habits forward while edging toward something new. Its forging is well made and its varied wide temper line is highly regarded, and the register notes that its state of preservation is good.

What to Look For in the Blade

Two eras meet in this sword. Its point is a kamasu-kissaki, a narrow, drawn-out tip named for the slender mouth of the barracuda and typical of early blades. The back is rounded (maru-mune), and the blade keeps a faint inward curve toward the edge (uchizori) rather than the outward sweep of a later tachi. These are archaic traits, the marks of the older straight sword.

The steel itself rewards a slow look. The forging shows a flowing wood-grain pattern (itame) that stands slightly proud of the surface, scattered with bright crystalline ji-nie and threaded with the dark lines called chikei that trace the folds of the metal. Along the edge runs a broad straight temper line (hiro-suguha), broken here and there by irregular and doubled lines, with streaks of sunagashi drifting through it like sand pulled along by a current. The smith even hardened part of the back of the blade, an effect known as mune-yaki. Across the surface the bright martensite crystals called nie lie thick and gather into clusters.

The tang is original and never shortened (ubu), a condition that is rare and prized in a blade this old. It is cut across in a single line, then stepped down on the edge side into a two-stage shape likened to a pheasant's thigh (kijimata), finishing in a rounded, chestnut-like end. A single hole is pierced at the tip of the tang for the cord (tenuki-no-o) once used to carry the sword, one more holdover from the older way of wearing a blade.

Where to See Swords of This Age

This sword belongs to a private owner and is not open to the public, and the national register names no museum or temple where it is kept. Travelers who want to understand its world are better served by the public collections that hold related blades.

The closest comparisons sit in the Shōsōin at Tōdai-ji in Nara, whose treasures are shown to the public each autumn at the Shōsōin Exhibition held by the Nara National Museum. In Tokyo, the Tokyo National Museum keeps the Important Cultural Property straight sword known as Suiryūken, an eighth-century blade linked by tradition to Emperor Shōmu, and rotates other early swords through its galleries. Two straight swords designated National Treasures, the Heishishōrin-ken and the Shichisei-ken, are held at Shitennō-ji in Osaka, and a further National Treasure straight sword survives at Ōmura Shrine in Kōchi Prefecture. For the craft of the sword more broadly, the Japan Sword Museum in the Sumida district of Tokyo gives a focused introduction to forging, polishing, and appraisal.