Naginata Structure and Standards: Blade Length, Tang, Curvature and Its Modern Role in Women's Martial Arts

What is the Naginata?

The naginata is a uniquely Japanese sword-type weapon with a large curved blade attached to the end of a long shaft, and is a polearm that functioned fundamentally differently from the katana or tachi. The theory that the name naginata derives from the action of "sweeping" (nagi-harau) is widely accepted, and the weapon has a structure specialized for slashing strikes from horseback and sweeping motions by foot soldiers.

From the perspective of sword collectors, the blade (edge portion) of a naginata is evaluated as an independent work of art. The nakago has a characteristically long length, and the hamon and jihada are appreciated from the same perspective as Japanese swords.

The Basic Structure of the Naginata — Names and Functions of Each Part

The blade of a naginata is broadly divided into the "mi" (blade body) and "nakago" (tang). The most significant difference from a katana is that the nakago is extremely long (sometimes comprising more than one-third of the entire weapon), with a long wooden shaft (from the ishizuki to the kuwagata section) inserted into it.

Hachou (blade length) refers to the length of the cutting edge. In historical naginata, this typically ranged from 60 to 90 centimeters, though some large naginata from the Nanboku-Chō period exceeded one meter. In modern martial arts competition naginata, strict standards are set for blade length.

Regarding sori (curvature), naginata blades typically have a greater inward curve than tachi. This strong curvature is optimized for the sweeping motions of a polearm, and as the blade edge is subjected to centrifugal force while tracing a large arc, it increases cutting power.

The hi (groove in the blade) commonly seen in naginata blades serve to reduce weight while maintaining rigidity. The position, shape, and number of hi vary depending on the school and period of the maker, making them important points for appreciation.

Naginata Forms Across Eras — From the Heian to the Early Modern Period

The naginata appeared in samurai society from the late Heian period onward, and frequently appears in battle scrolls from the late Heian to Kamakura periods, showing warriors wielding naginata. Very few examples of naginata from this period survive; the majority were later converted into "naginata-naoshi" (discussed below) by being remade into tachi or katana.

From the late Kamakura period through the Nanboku-Chō period, naginata became larger, and massive blades called "ōnaginata" (great naginata) appeared. This was an era when long blades were considered advantageous in battle, and naginata followed this trend. Many of the blades currently circulating as "naginata-naoshi" are remade versions of ōnaginata from this period.

From the late Muromachi period through the Sengoku period, the rise of the yari (spear) diminished the naginata's role on the battlefield. This was because the "yaribu­suma" (dense spear formation) tactic, where infantry fought in tight formations, became widespread, making the long naginata disadvantageous in close-quarters combat.

Entering the Edo period, the naginata was redefined as a martial art and self-defense weapon for samurai women, becoming a symbolic element of female martial arts practice in samurai households. This tradition of "onna naginata" (female naginata) continues into modern naginata martial arts.

Naginata-naoshi — How to Distinguish Altered Blades

"Naginata-naoshi" refers to a naginata blade that has been altered into a katana (or wakizashi or tachi), and is an important concept in Japanese sword collecting. The majority were naginata from the Kamakura to Nanboku-Chō periods that were shortened to a more practical length and remade into katana or wakizashi.

A characteristic feature of naginata-naoshi is the distinctive inward curve, "uchi­zori." While the curvature of a normal katana curves away from the cutting edge (toward the spine), blades remade from naginata may retain the so-called "naginata-sori," curving toward the edge. Additionally, the blade tends to become narrower toward the point compared to the base, often giving an overall slender appearance.

When the NBTHK certification clearly marks a blade as "naginata-naoshi," the blade's provenance as a naginata is officially recognized. Among the masterpieces of naginata-naoshi, many were created by excellent craftsmen from the late Heian to Kamakura periods, making them particularly popular with collectors of ko-to.

Standards for Modern Martial Arts "Naginata"

Modern martial arts competition "naginata" is based on standards set by the All Japan Naginata Federation, using bamboo or wooden mock naginata for competition and kata demonstrations. This refers to competition-specific standards distinct from actual Japanese sword naginata.

Competition naginata have an overall length of approximately 210-230 centimeters (women) to 230-250 centimeters (men), with prescribed ratios and weight specifications for the shaft and blade portions. In kata demonstrations, actual cutting motions are practiced as formal sequences, and in tournaments, competitors wear protective gear and engage in striking competitions using "shinai" (bamboo mock weapons).

Modern naginata is overwhelmingly dominated by female competitors, with substantial numbers of participants in high school and university club activities. This reflects the ancient tradition of the naginata as a "woman's weapon" continuing into the present day.

Points for Appreciating the Naginata — Advice for Collectors

Here are key points for appreciating and collecting naginata blades as works of art.

First, examine the position and type of hi. The condition of the "bō-hi" (rod groove) or "soe-hi" (auxiliary groove) commonly found on naginata serves as an indicator of polishing quality and wear from use.

Next, examine the shape and length of the nakago. Naginata nakago are longer than those of katana, and typically feature unique file marks. When a signature (mei) is present, it is usually positioned in the center to lower portion of the nakago.

Regarding hamon, naginata display diverse hamon patterns, ranging from gentle suguha-type designs to bold, irregular midare-type patterns. Naginata influenced by Bizen-den and Yamato-den traditions from the Kamakura period are particularly notable for their distinguished jihada and hamon.

When collecting naginata, establishing market prices is more difficult than with katana due to limited circulation. Transactions through specialized sword dealers or reliable auctions are recommended. The presence or absence of a certification is equally important as with katana. In particular, for naginata-naoshi, the availability of documentation recording the original form before alteration affects value assessment.