Kenukigata Tachi: The Unique Handle Design of Early Heian Swords and Ancient Japanese Sword Styles

What is the Keぬki-Gata Tachi? — A Special Structure Where Blade and Hilt Are Fused

The keぬki-gata tachi (毛抜形太刀) is a special style of sword crafted during the early to mid-Heian period. Its most distinctive feature is that the blade and nakago are forged as a single unit, and moreover, the "shingane" (core iron) that forms the core of the tsuka (hilt) is made from the same iron as the blade. Through this structure, the blade, nakago, and hilt core literally become a "single sheet of metal," fundamentally different from the insertion-style construction of later tachi and uchigatana, where the nakago is fitted into the hilt.

The name "keぬki-gata" derives from the sukashigori (openwork) design of the hilt. The parallel double-legged openwork patterns resembled the shape of keぬki (tweezer) tools used by noble women of the time—metal implements shaped like pincers. The openwork pattern served not merely as decoration but also had practical functions in reducing weight and improving grip comfort.

Manufacturing Methods — Technical Challenges of Heian Swordsmiths

Crafting a keぬki-gata tachi represented a high level of technical challenge for swordsmiths of the era. The forging process of integrating blade, nakago, and hilt core required achieving different hardness and shapes in each section. The blade required high-carbon steel for cutting ability, while the hilt needed lower-carbon steel with greater ductility to prevent breakage—this contradiction had to be resolved within a single integrated structure.

How early Heian swordsmiths solved this problem has been partially clarified through analysis of surviving keぬki-gata tachi. Examination of the jigane (base metal) composition reveals different forging methods between the blade and hilt sections, suggesting intentional variation in carbon content. The openwork carving of the hilt was further refined after forging using yaseuri (files) and tagane (chisels), demonstrating the high level of metalworking technique of the period.

The blade length typically ranged from two to two-and-a-half shaku (approximately 60–76 centimeters), somewhat shorter than later tachi. The curve followed a koshshiori (waist curve) pattern, with graceful rounded lines throughout the blade. The kissaki (point) was modest in size, displaying the "small kissaki" form characteristic of the Heian period.

Surviving Keぬki-Gata Tachi — National Treasures and Important Cultural Properties

Surviving keぬki-gata tachi are rare, with nearly all designated as National Treasures or Important Cultural Properties. Among the most famous are examples held in the Tokyo National Museum, with portions of the "kokushshitsu tachi" believed to display keぬki-gata characteristics.

Particularly noteworthy are keぬki-gata tachi that survive as votive offerings at shrines and temples throughout the country. The treasure houses of Kasuga Taisha (Nara) and Atsuta Jingú (Aichi) preserve multiple Heian-period votive keぬki-gata tachi, whose decorative sophistication continues to astonish modern researchers. Many feature kin-gin zougan (gold and silver inlay) and raden (mother-of-pearl inlay) work, demonstrating that both practical utility as weapons and artistic refinement coexisted.

The keぬki-gata tachi displayed in Atsuta Jingú's treasure museum features not only openwork carving on the hilt but also intricate patterns on the nakago section, clearly showing the aesthetic role of swords in Heian noble society. Keぬki-gata tachi used and offered at ritual ceremonies had a strong character as "gireitou" (ceremonial swords) distinct from practical battlefield weapons.

Historical Position of the Keぬki-Gata Tachi — Transition from Ancient to Medieval Periods

The early Heian period (circa 9th century) when keぬki-gata tachi were made represents a transitional phase in Japanese sword styles, moving from "joukoutou" (ancient swords) with their straight blades to curved tachi. The keぬki-gata tachi occupied an important intermediate position in this transition, serving as a precursor to the "fully developed curved tachi" that would later be perfected.

While building on the straight-blade technology transmitted from the continent (China and the Korean Peninsula), keぬki-gata tachi played an important experimental role in the evolution toward shapes suited to Japanese mounted warfare tactics. Though the integrated-forging structural approach was later abandoned, the decorative openwork design is believed to have influenced later sword fittings, particularly tsuba and menuki designs.

Sword Culture Before the Establishment of Samurai Society

The period when keぬki-gata tachi were made was also an era when "samurai" had not yet emerged as a clearly defined social class. The primary users of swords were imperial court nobility, influential clan leaders, and the kebiishi (palace police) who guarded the capital—a social context different from the sword-as-samurai-soul philosophy developed after the Sengoku period.

In that era, swords were part of court ritual and noble formal dress, with aesthetic appeal emphasized. The intricate ornamentation of keぬki-gata tachi responded to such social demands. As warrior governments became established and swords gained character as practical weapons, the complex integrated-forging structure of keぬki-gata tachi fell out of use due to manufacturing costs and durability concerns.

The keぬki-gata tachi is a product of an age when Japanese swords functioned not merely as weapons but as expressions of social status, authority, and aesthetic sensibility. Their distinctive hilt structure and refined ornamentation continue to fascinate researchers and enthusiasts today as precious testimony to the aesthetic sophistication of Heian court culture and the technical pinnacle reached by contemporary metalworkers and swordsmiths.