Core Vocabulary

This is the hub’s reference page — read it once now, then return whenever a later section uses a word you’ve half-forgotten. Terms marked ★ are the ones that appear constantly; internalize those first. Japanese terms are used throughout the literature untranslated, so there’s no avoiding them; the good news is that forty covers nearly everything.

Most of the blade-anatomy terms are easier to see than to read:

Steel and fire

• satetsu — iron-bearing black sand, collected from rivers and hillsides; the raw material of traditional sword steel. Unusually low in phosphorus and sulfur, which is much of why it was worth the trouble.
• tatara — the clay bloomery furnace that smelts satetsu and charcoal into steel over about three days, without ever fully melting the iron. Rebuilt for every smelt.
• kera — the multi-tonne spongy mass of raw steel a tatara produces, broken up and sorted by quality.
• ★ tamahagane — “jewel steel”: the best, highest-carbon fraction of the kera, reserved for sword edges and skins.
• kawagane — skin steel: high-carbon, heavily folded steel forming a blade’s outer surface and edge.
• shingane — core steel: low-carbon, tough steel hidden inside the blade. Kawagane, unlike shingane, is meant to be seen and to cut.
• tanren — the fold-and-weld forging cycle that purifies and homogenizes the steel; the source of the surface grain.
• ★ yaki-ire — the quench: heating the clay-coated blade to about 800 °C and plunging it into water. Creates the hard edge, the hamon, and most of the curvature, and carries the risk of cracking the blade.

The blade

• ★ sugata — a blade’s overall form: length, curvature, proportions, point. The first thing an appraiser reads, because sugata tracks era.
• nagasa — blade length, measured in a straight line from tip to the notch where the tang begins. Legal and traditional classifications key off it.
• ★ sori — curvature: the maximum distance between the spine and a straight line from tip to tang notch. Where along the blade the curve sits deepest is itself a dating clue.
• kissaki — the point section, set off by its own geometry; its size (small, medium, large) is a strong era indicator.
• bōshi — the hamon’s continuation inside the kissaki. Appraisers weight it heavily because it’s hard to fake and survives repolishing poorly.
• mune — the spine, the unsharpened back of the blade.
• ha — the edge; the hardened cutting side. Also in compounds: hasaki (the very edge line), hagire (a crack in it — fatal).
• shinogi — the longitudinal ridge line between edge bevel and spine surface; standard long swords are shinogi-zukuri, “ridge-line construction.”
• ★ nakago — the tang: the unpolished tail of the blade inside the handle, carrying the signature and file marks. Its rust patina is a primary dating tool, which is why cleaning a nakago destroys value.
• mei — the inscription chiseled into the tang: maker, sometimes province, date, or owner. A blade with no mei is mumei, “unsigned.”
• ★ hamon — the temper line: the visible boundary of the quench-hardened edge steel, in shapes from dead-straight (suguha) to waves and clove-flower lobes. Structural, not decorative.
• ★ jigane / jihada — jigane is the visible surface steel itself; jihada is its grain pattern (wood-grain itame, straight masame, burl mokume), the record of the folding.
• ★ nie — hardened-steel crystals large enough to see individually: a frost-like sparkle along the hamon. Produced by hotter, harder quenching.
• ★ nioi — the same crystals too fine to resolve by eye: a continuous mist. Nie and nioi, mixed in different proportions, are the connoisseur’s first-order signature of a school.
• hataraki — “activities”: the small bright features in and around the hamon (streaks, lightning lines, dots) that appraisers read as evidence of technique and quality.

Forms and mountings

• tachi — the older long sword, worn slung edge-down with armor; typically longer and more deeply curved. Signed on the side that faces out when worn — which is how you tell a tachi’s tang from a katana’s.
• ★ katana — the long sword worn thrust through the sash edge-up, standard from the Muromachi period on; drawn and cut in one motion. Legally, a curved blade 60.6 cm (two shaku) or longer.
• wakizashi — the companion short sword, 30.3–60.6 cm; paired with a katana it forms the daishō, the samurai’s two-sword set.
• tantō — a dagger under 30.3 cm, mostly flat-sided (no ridge line); a major art form of the Kamakura period.
• ★ koshirae — a sword’s full formal mounting: lacquered scabbard, wrapped hilt, guard, and fittings, made by separate specialists.
• shirasaya — the plain magnolia-wood “resting” mount a blade lives in for storage. Shirasaya, unlike koshirae, is not built to be worn or used.
• habaki — the fitted metal collar at the blade’s base that seats it in the scabbard and keeps the edge from touching anything. Every blade gets its own, hand-made.
• tsuba — the guard: a field of art collecting in its own right, from austere pierced iron to lavish soft-metal work.

Judgment, people, and eras

• tōshō (also katana-kaji) — the swordsmith: licensed in modern Japan after a five-year apprenticeship, and legally limited in monthly output.
• togishi — the sword polisher: a separate profession, roughly ten years to competence, responsible for both the blade’s geometry and its legibility.
• ★ kantei — appraisal: attributing a blade to an era, school, and ideally an individual smith from its physical evidence — practiced blind on unsigned blades as the field’s core skill and sport.
• gimei — a fake signature: far more common than newcomers expect, which is why the rule is “judge the blade, then the mei,” never the reverse.
• suriage — a blade shortened from the tang end, usually to convert a long tachi to katana length; ō-suriage (fully shortened) blades lose their signatures, which is what makes kantei necessary.
• ★ gokaden — the “five traditions” (Yamashiro, Yamato, Bizen, Sōshū, Mino): the classical school framework used to organize almost all old-sword appraisal.
• kotō / shintō / shinshintō / gendaitō — the four period labels: “old swords” (to ~1596), “new swords” (Edo), “new-new swords” (~1764–1876), and modern blades. A newly made sword is a shinsakutō.
• NBTHK — the Society for Preservation of the Japanese Art Sword: runs the modern tatara, the Japanese Sword Museum, and the shinsa authentication system whose papers anchor the market.