The Art of the Sayashi: Crafting the Perfect Scabbard for the Japanese Sword

The World of Saya-shi Craftspeople—Giving the Sword Blade a "Home" Through Skill

A Japanese sword does not function as a "weapon" merely with its blade completed. Only when the togi-shi polishes the edge, the tsuka-maki-shi breathes life into the hilt, the kinko-shi forges the metal fittings, and the saya-shi creates a "home" to hold the blade does a single Japanese sword finally become complete.

A saya-shi is a craftsperson who specializes in making sayas. In the sword trade, specialization is thorough; the saya-shi handles everything related to the saya—from material selection, wood planning, shaping, koiguchi adjustment, and lacquer undercoating.

The role of the saya extends beyond merely storing the blade. It ensures safety during drawing and sheathing, protects the blade from moisture, rust, and impact, and also functioned as a decorative item that made visible the status and aesthetic sensibility of the warrior. During the Edo period, there were saya-shi employed by the shogunal family and feudal lords, and their techniques were handed down through generations under a master-apprentice system. Even after the Meiji period, when demand declined sharply due to the Sword Abolishment Edict, the craft maintained its vitality in the context of preserving and restoring art swords, continuing to the present day.

Material Selection—Ho Wood, Urushi, and Samekawa

The primary material of the saya is ho wood (a native Japanese hardwood that is relatively soft and lightweight). Why has ho wood been consistently chosen among countless timber options? The answer lies in two properties: "it does not damage the blade" and "it maintains consistent humidity inside the saya."

Ho wood's cellular structure contains moderate oil content and elasticity, making it unlikely to induce rust even with direct contact with the steel blade. Wood also has the function of naturally regulating the environment inside the saya through repeated absorption and release of moisture. Saya-shi typically use wood that has undergone natural drying for several years to over a decade, carefully selecting areas with uniform moisture content. If insufficiently dried wood is used, warping or cracking occurs after completion, changing the shape of the saya.

Urushi (lacquer) is a finishing material applied to the outside of the saya, serving three functions: waterproofing, moisture resistance, and impact resistance. For shirasaya (sayas intended for storage), the principle is to apply no urushi, preserving the white natural surface of the ho wood—this allows easy visual inspection of the blade condition and ensures breathability. Sayas for elaborate koshirae receive diverse techniques such as black urushi coating, red urushi coating, and kawari-nuri. Kawari-nuri techniques include nashiji, ishime, and sabi-nuri, sophisticated decorative methods that developed during the Edo period.

Samekawa (shark skin) consists primarily of dried ray skin, possessing a distinctive granular surface. While widely known as a wrapping material for the tsuka, it is sometimes used in the form of "samemaki" on the exterior of the saya. In modern times, sourcing has become increasingly difficult, and no substitute material has yet been found that matches genuine samekawa.

Completely Bespoke Manufacturing Process

Saya production is completely bespoke. Since each blade differs in length, width at the base, width at the tip, thickness (kasane), curve of the sori, and shape of the nakago, mass production is fundamentally impossible. In the world of art swords and honkatana, off-the-shelf products have no application whatsoever.

1. Measurement and Wood Planning: The blade is measured and all dimensions are recorded on a paper template. In wood planning, the direction of the grain affects strength and future shrinkage, so experienced saya-shi read the wood's characteristics at this stage. Decisions made at this stage influence all subsequent processes.
2. Rough Shaping and Toudou Carving: The ho wood is split vertically into two pieces, and a groove following the blade's outline—the toudou (blade channel)—is carved into each interior surface. The precision of this groove is the fundamental process that determines the quality of the entire saya. The two pieces are joined using hagizawase and the exterior form is refined.
3. Finish Shaping and Koiguchi Adjustment: The exterior is finished thin and uniformly, and the weight balance is adjusted. The final adjustment of the koiguchi is performed at this stage, representing the moment where the saya-shi's skill is most tested.
4. Lacquer Undercoating: For a shirasaya, completion requires only the impregnation of thin lacquer for sealing the wood. For sayas with elaborate koshirae, multiple applications of base coat, middle coat, and top coat are applied and sanded repeatedly. After each lacquer application, the piece must be dried in a high-humidity chamber (muro), and this process alone can take from weeks to several months.

A single shirasaya typically takes approximately one week, while one with elaborate koshirae including lacquer work typically extends to several months.

Koiguchi Precision—The Ultimate Indicator of Saya Quality

"Judge the saya's quality by its koiguchi"—this phrase, commonly heard in sword circles, is no exaggeration. The koiguchi is the opening of the saya, and its precision directly determines functionality, safety, and aesthetics.

The inner diameter of the koiguchi is designed with clearance measured in tens of micrometers (μm) relative to the thickness of the blade's spine (mune) and edge (ha). If the gap is too large, the blade will move within the saya during sheathing and damage the interior walls. Conversely, if too tight, strong friction occurs during drawing, and in the worst case, the wood of the koiguchi can split.

The ideal that master saya-shi pursue is a state where "the blade does not fall by its own weight, yet is drawn silently with a gentle pull." The sheathed blade retains enough grip to not fall naturally when the saya is inverted, while releasing smoothly on the first gentle draw—such a precise friction coefficient is achieved through shaping work in fractions of a millimeter.

To achieve this precision, at the final adjustment stage, the saya-shi repeatedly inserts the blade into the saya while shaving away the inner wall of the koiguchi in minute increments. This is a completely irreversible one-shot process—failure means starting the entire saya over.

Contemporary Saya-shi and the Succession Problem

Currently, only around dozens of full-time saya-shi craftspeople are said to exist nationwide. On the demand side, the expansion of iaido populations has created a stable source of orders for iaito saya repair and creation, and requests for restoration and production from overseas Japanese sword collectors and museums are on an increasing trend. However, income stability is low, and even renowned saya-shi often produce only dozens of new pieces per year.

The succession problem is grave. It requires a minimum of five to ten years of apprenticeship to reach a level of independence, with no income support during that period. The difficulty for young people today in enduring this apprenticeship while facing living expenses is a structural issue shared with other traditional crafts such as pottery, textile dyeing, and lacquerware. Some saya-shi are working to raise awareness and secure successors through partnerships with sword museums and by sharing their techniques via video and social media.

The Criteria for "Excellent Sayas" Pursued by Master Saya-shi

The conditions for an "excellent saya" as commonly described by master saya-shi are condensed into three principles.

• Complete Dialogue with the Blade: An excellent saya precisely embodies the blade's individuality. The length, curvature (sori), and center of gravity are all reflected in the saya's form, creating a natural fit as though the blade is "breathing" within the saya.
• Resistance to Aging: Wood is alive. It expands and contracts with the seasons, and the sori may change during long storage. An excellent saya possesses the stability to withstand decades of use through wood planning and drying techniques that anticipate such changes. The phrase "not just a good saya today, but still a good saya a hundred years from now" is a principle passed down among craftspeople.
• Respect for the User: The subtle sound when sheathing the blade, the feel in the hand at the moment of drawing, the weight balance when worn at the hip—all of these are designed to complement the user's movements and actions.

Through TOUKENZA, we seek to share the profound experience of Japanese sword culture by delivering swords that embody the mastery of such saya-shi craftsmanship.