The World of Koshirae — A Complete Guide to Japanese Sword Mountings and the Craftspeople Who Make Them

The saya is the scabbard — the outer housing that protects the blade when not in use. Its construction begins with honoki (magnolia wood), which is split, hollowed to receive the blade with precise tolerances, and then rejoined. The precision of this hollowing is critical: the blade must slide smoothly without metal-to-metal contact with the scabbard's interior, while fitting snugly enough to stay in place during movement. A saya-shi who truly knows their craft shapes the interior around the specific contours of the specific blade.

The finished wood core is then covered in urushi lacquer — a process that may involve dozens of layers applied over weeks, each layer dried and polished before the next is applied. The variety of urushi finishes is enormous: kuro nuri (black gloss), roiro nuri (mirror black), nashiji (gold-flecked "pear skin"), aogai (mother-of-pearl inlay), and many others, each with its own technical demands and aesthetic character. A fine Edo-period saya in perfect condition is a technically demanding lacquer work in its own right — and is valued as such by connoisseurs of Japanese lacquer as well as sword collectors.

The saya incorporates several fixed fittings: the koiguchi (口 — the scabbard mouth, traditionally fitted with buffalo horn), the kurikata (栗形 — the knob through which the sageo cord is threaded), and the kojiri (鐺 — the protective fitting at the scabbard's tip, also traditionally buffalo horn).

The tsuka is the handle — built over the nakago (tang) of the blade, covered in samegawa (ray skin), and wrapped in silk or cotton ito (cord) in patterns that vary by style and period. For a complete guide to the tsuka and how to evaluate its quality, see our dedicated article The Tsuka — How to Tell a Genuine Handle from a Factory-Made Imitation.

The tsuka's construction involves the collaboration of several craftspeople: the saya-shi who shapes the wooden core (tsuka-gaki), the specialist who applies the samegawa, and the tsukamaki-shi who performs the ito wrapping in the correct technique — including the alternating moroneri twist that locks each section of the wrap independently. The menuki (handle ornaments) are positioned beneath the wrap as both grip aid and decorative element. The quality of the tsuka assembly is the most immediately tangible indicator of a koshirae's overall craft standard — and one of the most reliably diagnostic indicators of factory-made imitation versus genuine traditional craft.

The tsuba is the guard — the plate positioned between blade and handle that protects the hand and marks the visual centrepiece of the koshirae. Among all koshirae components, the tsuba is most celebrated as an independent art form. Tsuba are made from iron, brass, copper, or alloys such as shakudo (copper-gold) and shibuichi (copper-silver). Decorative techniques include sukashi (cut-through openwork), takabori (relief carving), zogan (inlay), and sukidashi (low-relief sculpture). By the Edo period, specialist tsuba makers had established their own schools and hereditary lineages, including the Goto, Hirata, and Yokoya families.

The tsuba's cultural weight in Japanese sword history is unique among koshirae components. Whole collecting disciplines exist around specific schools of tsuba making. Tsuba are bought, sold, and inherited independently of blades. The NBTHK certifies tsuba independently through its tosogu kantei process — a named, documented tsuba by a recognised school can be authenticated and valued entirely separately from any blade it accompanies. A Goto school tsuba, a Yokoya Somin work, or a significant iron tsuba by the Owari tradition may command prices measured in tens of thousands of dollars — independent of any blade.

Iconographic themes on tsuba range from natural subjects (seasonal flowers, birds, landscapes) to mythological scenes, Buddhist and Shinto imagery, and the heraldic devices of specific daimyo families. The motif choice was not arbitrary — it communicated the owner's cultural references, spiritual affiliations, and social standing to every samurai who encountered them.

The habaki is the metal collar fitted directly to the blade at the base — the single most mechanically critical component of the entire koshirae. Its function is dual: it locks the blade in the saya by engaging the koiguchi (scabbard mouth), and it provides a stable base against which the tsuba and seppa rest. The fit of the habaki to the specific blade is as precise as the fit of the saya — it is made for this blade alone, to tolerances measured in fractions of a millimetre.

Habaki are most commonly made from copper, gold-foiled copper (kinpuku), or solid gold on very fine pieces. The surface treatment varies: plain polished metal, hammered texture, or decorative file work. On museum-grade blades, the habaki may itself be a work of art — gold habaki with carved motifs are found on the most prestigious pieces.

The seppa are the two thin metal washers placed on either side of the tsuba, between the tsuba and the habaki on one side and the fuchi on the other. Seppa are thin metal spacers placed on either side of the tsuba to achieve a precise fit. Despite their apparent simplicity, correct seppa are essential — an ill-fitting tsuba that wobbles is almost always a seppa problem, and worn or missing seppa are one of the most common issues in period koshirae requiring restoration.

The fuchi is the metal collar at the guard end of the handle — the ring of metal between the tsuba and the tsuka's wrapped surface. The kashira is the pommel cap at the far end of the handle, securing the final knot of the ito wrap. These two components are invariably made as a matched pair by the same metalworker — in the same material, in the same style, with matching or complementary decorative motifs. A fuchi and kashira from different sources, however beautiful individually, represent an incomplete or restored koshirae.

The fuchi-kashira is where the metalworker's artistic contribution to the koshirae is most concentrated. A matched Goto school fuchi-kashira in shakudo (shakudo nunome zogan) with the Tokugawa aoi-mon (hollyhock crest) is a historically significant piece with its own authentication papers. When evaluating a koshirae's completeness and integrity, the matching of the fuchi-kashira — same artist, same school, same material, complementary motif — is the primary diagnostic. Mismatched fuchi-kashira are among the most common indicators of a koshirae assembled from separate sources rather than created as a unified commission.

Menuki are the small metal ornaments positioned beneath the tsuka-ito wrap on both faces of the handle. Their dual role — functional grip enhancement and decorative element — makes them unique among koshirae components. Positioned at the natural pressure points of the gripping hand, the three-dimensional menuki create subtle contours beneath the ito wrap that help locate and stabilise the grip without conscious thought.

Menuki are made in pairs — one for the omote (outer) face and one for the ura (inner) face of the tsuka, offset from each other rather than directly opposite. They should be positioned correctly in terms of tenchi — orientation — with the motif facing the correct direction for each face. A reversed or misoriented menuki is a reliable indicator of incorrect remounting.

In the Goto school's tradition, menuki, kozuka, and kogai were collectively known as mitokoro-mono (三所物 — "three-place things") — the three small fittings that completed a formal koshirae. A complete matched set of mitokoro-mono by the Goto school — menuki, kozuka handle, and kogai — is among the most prestigious complete koshirae fitting sets in the tradition, and has been collected independently of any blade since the Edo period.

The sageo is the cord threaded through the kurikata on the saya and used to secure the sword to the wearer's belt or to bind the saya in specific situations. In traditional wearing, the sageo's colour and material communicated the wearer's status — high-ranking samurai wore sageo in specific colours corresponding to their position. For display and collection purposes, the sageo's colour should complement the overall colour scheme of the koshirae. A period-correct sageo in the appropriate colour and material for the koshirae's provenance adds to the ensemble's historical completeness. A sageo in the wrong colour — or a modern replacement in synthetic material — is a minor but detectable indication of restoration or replacement.