The Mekugishi: Specialized Craftsmen Who Secure the Sword's Core — Techniques and Lineage

About Mekugi Craftsmen—The Importance of Invisible Work

In Japanese swords, the small component that secures the blade (nakago) to the handle (tsuka) is called a "mekugi." Typically made of bamboo, it passes through the mekugi-ana (mekugi hole) in both the nakago and handle wood, unifying the entire sword as one piece. The craftsman who specializes in making these mekugi is called a "mekugi-shi," though in modern times few even within the sword industry know the name. For other work by decorative metal fittings craftsmen, please also refer to A Day in the Life of a Habaki Craftsman.

The mekugi-shi is one of the least glamorous yet most functionally important specializations in the sword industry. If the mekugi is not properly made, a fatal danger arises—the blade could separate from the handle during a draw. For the Japanese sword as a weapon, this was literally a matter of life and death. The work of the mekugi-shi was, for a samurai, literally a matter of trusting it with one's life.

Mekugi Materials and Types—From Bamboo to Bone

Bamboo is the most widely used material for mekugi. Bamboo mekugi possess elasticity, resist compression well, and have the property of gradually hardening with age. Bamboo resists splitting along the grain and maintains consistent strength against lateral pressure. Sword smiths favor bamboo mekugi as standard because these properties are most superior from a practical standpoint.

However, bamboo is not the only material used for mekugi. The materials used for mekugi and their characteristics are as follows.

• Bamboo: Possesses elasticity, resists compression, and gradually hardens with age. Resists splitting along the grain and maintains consistent strength against lateral pressure, making it chosen for practical combat swords.
• Ivory, whale baleen, and water buffalo horn: Were sometimes used in ceremonial and formal presentation swords.
• Metal (those covered in gold or silver for decoration): Particularly applied to the formal swords of daimyo families, serving as part of the aesthetic of the sword mounting (koshirae). Unlike bamboo, these present rust issues, but offer greater strength in compensation. However, thermal expansion creates the risk of loosening due to temperature fluctuations, so these were primarily used for decorative formal presentation swords.

The Technical System of Mekugi Craftsmen—Hole Alignment and Peg Adjustment

The primary techniques of the mekugi-shi fall into two broad categories.

• Precise measurement of the mekugi hole and cutting of the mekugi
• Confirmation and correction of the alignment between the nakago hole and the mekugi hole in the handle wood

In the production of bamboo mekugi, the mekugi-shi first carefully selects the bamboo to be used. Madake and mouzou-chiku are commonly used, but since strength varies according to node spacing, fiber density, and drying condition, experienced mekugi-shi are particular about the source and harvesting season of the bamboo. Bamboo harvested in winter has low moisture content and dense fibers, and is considered superior as mekugi material.

After rough-cutting the bamboo to mekugi size, it is precisely shaped with files and small blades. The cross-section of the mekugi is often elliptical, which matches the shape of the mekugi hole. The elliptical mekugi has a clear fixing direction and is designed to prevent rotation within the handle.

In the final finishing, the mekugi-shi actually inserts it into the sword to confirm the fixing strength. If the mekugi is too loose, the blade will move; if too tight, it damages the mekugi hole. It takes years of experience to master the subtle sense of this perfect "fit" (kangou).

Historical Lineage—The Formation and Specialization of the Mekugi Craftsman

The formation of the mekugi-shi as an independent specialty is considered to have occurred around the middle of the Edo period, when specialization of craftsmen in the sword industry was advancing. Before that time, saya-shi (scabbard craftsmen) and tsuka-maki-shi (handle-wrapping craftsmen) often also undertook mekugi production. The background to advancing specialization lies in the flourishing sword culture of the Edo period and the trend toward refinement and specialization of sword fittings (koshirae) in samurai society.

Even after establishing itself as an independent craftsman, the mekugi-shi maintained close cooperative relationships with saya-shi and tsuka-maki-shi. In completing the mounting of a single sword, the work of each craftsman was mutually interdependent, and the dimensions of the mekugi were inseparably linked to the structure of the handle wood and the shape of the nakago. For the specialist craft that oversees the entire sword mounting, see the discussion in The Koshirae-shi, a Specialist Craftsman.

The Sword Abolition Edict (1876) from the late Edo through Meiji periods dealt a severe blow to sword craftsmen overall, including mekugi-shi. With dramatic decline in demand, many full-time mekugi-shi were forced to close their businesses, and in many regions the techniques disappeared entirely. In the present day, full-time craftsmen calling themselves mekugi-shi are extremely rare, and the techniques are maintained only tenuously, passed on by saya-shi and togi-shi (polishing craftsmen).

Mekugi Replacement in Practice—Knowledge Sword Owners Should Know

For sword owners, the mekugi becomes a subject of regular maintenance. Bamboo mekugi deteriorate with age and gradually become loose due to expansion and contraction from changes in drying and humidity. As a guideline, replacement is recommended around every 10 to 20 years, though this varies significantly depending on storage conditions.

Replacing the mekugi is not easy without specialized knowledge. Applying excessive force to the mekugi hole damages the nakago and can result in deformation of the hole, making repair difficult. Furthermore, the mekugi can induce rust at the junction with the blade, so it is important to choose a mekugi of appropriate material and dimensions.

It is most certain to request that specialized sword dealers or togi-shi (polishing craftsmen) inspect the condition of the mekugi. A properly maintained mekugi is a prerequisite for the safe storage, display, and use of the sword. The maintenance of the mekugi-shi as a profession is also a fundamental condition for correctly passing down the Japanese sword as a cultural treasure to future generations.