Kozuka and Kogai: The Utility and Artistry of Japanese Sword Side Tools

Kozuka and Kogai — The Samurai's "Versatile Utility Tools"

Japanese sword mountings (external fittings) sometimes house slender, elongated small tools called "kozuka" (small blade) and "kogai" (ornamental hairpin) on the sides of the scabbard. Though unrelated to the sword's combat function, these were practical tools frequently used in samurai daily life, while simultaneously serving as artistic pieces that embodied the metalworking craftsman's skill and aesthetic sensibility.

Kozuka comprises a handle (grip) and a small blade (kogata-na) integrated as one unit, stored in a "kozuka-mizo" (kozuka groove) created on the front side of the scabbard. The small blade's edge was forged sharp and was used for various daily samurai tasks—cutting, scraping, and even serving in place of a brush. The handle portion is where the metalworking truly shines, decorated with refined techniques including inlay, hair-line engraving, and relief carving.

Kogai is a slender tool stored in a "kogai-mizo" (kogai groove) on the back side of the scabbard. Originally designed for binding and arranging hair, it functioned similarly to modern hairpins. However, on the battlefield, it is said to have also been used in a different manner—inserted into the ear of a severed head and tied with a wooden tag bearing the warlord's name. Like the kozuka, the kogai received the full artistry of the metalworking master, adorned with lavish decoration.

These two pieces are often viewed as a pair, and when their designs are unified, they are called "soroiomono" (matched sets). Often, these are combined with fuchi and kashira (ferrules and pommel) and menuki (grip ornaments) to create "mitokoro-mono" (three-piece sets) or "itsukoro-mono" (five-piece sets).

History — From Origins to the Edo Period's Golden Age

The origins of kozuka and kogai trace back to the Heian and Kamakura periods. Kozuka and kogai grooves were incorporated into tachi (long sword) mountings from early times, and these practical portable tools were cherished by samurai. Examples from this period are often of simple construction, prioritizing functionality over decoration.

With the advent of the Muromachi period, the artistic refinement of sword fittings accelerated rapidly. Metalworking artisans emerged as independent professionals separate from swordsmiths, and kozuka and kogai likewise became exquisitely crafted works of decorative art. After the Ōnin War and throughout the Sengoku period, daimyo competed in commissioning work from master craftsmen, resulting in remarkable diversification of sword fitting designs.

From the Azuchi-Momoyama period through the Edo period, groups of metalworking masters—including the Gotō family, the Umetada school, Higo metalworkers, and Nara metalworkers—successively established their own distinct traditions. In the peaceful Edo period, as the practical need for combat waned, the aesthetic refinement devoted to sword fittings became ever more sophisticated, and kozuka and kogai came to be treasured as symbolic furnishings that displayed a samurai's cultivation and wealth.

Master Craftsmen and Schools — A Genealogy of Technique and Beauty

Gotō family was a metalworking lineage that produced supreme-quality sword fittings across 17 generations from the late Muromachi period to the end of the shogunate. Since the founder, Gotō Yūjō, served the shogunal household, Gotō works occupied a special status within samurai society. Their works frequently featured auspicious motifs—cranes, turtles, plum blossoms, pines, dragons, and tigers—rendered with elevated taste through gold relief carving inlay on shakudo (copper-gold alloy) ground, and their refinement served as a model for other schools. Gotō kozuka are treated as "Gotō-mono" (works by Gotō), and some of the finest surviving examples are designated as Important Cultural Properties.

Nara metalworkers, represented by three master craftsmen—Sugiura Norioki, Nara Toshinaga, and Tsuchiya Yasuchika—worked in Edo during the 18th century, bringing innovation to the metalworking world through realistic expression that transcended conventional auspicious motifs. The precise depictions of insects, flowers, plants, and animals found in Yasuchika's works are acclaimed as paintings themselves faithfully rendered onto metal.

Higo metalworking developed under the patronage of the Kumamoto domain, with craftsmen such as Hayashi Matashichirō and Hirata Hikozo pursuing the pristine beauty of plain iron and unadorned design. The austere designs, stripped of ornamentation to the limit, enjoy enduring popularity as embodiments of the samurai's stoic integrity and strength.

Materials and Techniques — The Essence of Metalworking Art

Understanding materials and techniques is essential to appreciating kozuka and kogai.

Shakudo (copper-gold alloy) is regarded as the most elevated material. It is an alloy of copper with gold (3–6%) and a small amount of silver, which when given a patina treatment with plum vinegar or chemical solutions yields a distinctive deep purple-black hue. Following this is shibuichi, an alloy of copper and silver characterized by a refined silver-gray patina. Gold, silver, and iron were also employed as materials, each with its own distinct aesthetic appeal.

Techniques fall broadly into two categories: carving and inlay.

• Hair-line engraving (keori) is the fundamental technique of incising fine lines
• Single-side carving (katakiri-bori) creates shadow and depth by cutting bevels on only one side of the blade
• Round and relief carving (taka-bori) renders motifs in thick, three-dimensional form
• Inlay (zougan) includes techniques such as "cut-metal inlay" (kirikane zougan), where thin grooves are cut into a metal sheet and another metal is fit inside, and "textile-pattern inlay" (nunume zougan), where a textured surface is hammered with inlay metal. Combining these techniques achieves remarkably fine expression.

Designs range widely—from auspicious motifs and seasonal flowers and birds to scenes drawn from Chinese poetry and historical anecdotes, and scenes from kabuki and Noh theater. The chosen subjects reflect the era, school, and patron's taste and cultivation in which they were created, making each kozuka a primary historical document that speaks to the cultural context of its time.

An Introduction to Collecting and Appreciation

Compared to complete swords, kozuka and kogai hold appeal in that fine examples circulate at more accessible price points. Examples from general Edo period workshops begin in the tens of thousands of yen, while superior works by the Gotō family or Nara metalworkers can reach hundreds of thousands to millions of yen. Overseas auctions consistently show stable demand for Japanese sword fittings, and they are highly valued by Western collectors.

When appreciating these pieces, first examine the material's color and surface texture, then observe the depth of carving, the delicacy of lines, and the three-dimensional quality of relief sections. The luster of the finish and the natural rust patina developed over time are also considered in evaluation. Signatures (mei) can help identify the workshop or period, but since the Gotō family used the "Gotō" signature across generations, determining which generation requires comprehensive connoisseurship.

Conclusion — Samurai Aesthetic Sensibility Enshrined in Small Metalwork

Kozuka and kogai, though small enough to fit in the palm of a hand, are concentrated expressions of samurai practical wisdom and the pinnacle of metalworking art. While fulfilling mundane daily tasks, at the moment they rest in the scabbard they silently proclaim their owner's status and aesthetic refinement—this duality is the essential allure of kozuka and kogai.

Once you have grown accustomed to appreciating the sword blade itself, please direct your gaze to the side of the scabbard. There, in quiet repose, rests the small metalwork that transmits across centuries the dialogue between craftsman and samurai to the present day.