What Is Yasurime (鑢目)? Sword Tang File Marks Explained
Yasurime (鑢目) are the file marks a swordsmith deliberately cuts into the tang (nakago) of a Japanese sword — a directional pattern of filing that helps grip the handle and, crucially, serves as a signature clue in appraisal. The word means "file marks." Because the tang is left unpolished, the yasurime survive as the smith made them, and their direction and style are one of the workmanship traits an expert reads to attribute an unsigned blade or to test a signature's authenticity.
To a collector, yasurime are one of the most reliable tells on a nihonto. They are cheap to overlook and hard to fake correctly, which is exactly why they matter: a smith or school filed the nakago a certain way habitually, so the pattern is a fingerprint — and a place where forgers routinely slip up.
Where yasurime are and why they exist
Yasurime are cut across the nakago, the tang that sits hidden inside the handle. They serve a practical purpose — the roughened surface grips the wood of the tsuka and helps hold the blade firm — but their appraisal value comes from the fact that the tang is never polished. While the blade's surface is repolished over the centuries, the nakago and its file marks age and darken but are left untouched, preserving the smith's original hand.
That is why yasurime, alongside the shape of the tang, the finish of its tip (nakago-jiri), and the mei, form a package of evidence read together in kantei, the formal appraisal of a sword.
The main yasurime patterns
Filing direction is described by named patterns. The most common you will meet on a tang include:
- Kiri (切) — horizontal marks, cut straight across the tang at right angles to its length. Simple and widely used.
- Sujikai (筋違) — slanting marks running diagonally across the tang. One of the most common patterns.
- Katte-sagari (勝手下がり) — a gentle slant, filed slightly downward toward the edge; very frequently seen and associated with many mainstream schools.
- O-sujikai (大筋違) — a steep, pronounced diagonal slant.
- Higaki (檜垣) — cross-hatched marks in a lattice, like a cypress fence, formed by filing in two crossing directions.
- Kesho (化粧) — decorative "cosmetic" filing, common on later blades, with a border of marks framing the main pattern.
- Gyaku-sujikai (逆筋違) — a reverse slant, running the opposite way to sujikai.
Certain patterns lean toward certain traditions and periods, so the yasurime narrow down the field of possible smiths before the signature is even read.
Reading yasurime in appraisal
In kantei, yasurime are weighed together with the rest of the tang. An appraiser asks whether the pattern is consistent with the claimed smith or school, whether it matches the era's conventions, and — vitally — whether it agrees with the signature above it. A smith who habitually filed katte-sagari should not appear with an out-of-character higaki tang under a genuine signature.
Yasurime are especially useful on mumei (unsigned) blades, where there is no mei to read at all. Here the filing, the tang shape, and the workmanship of the blade carry the whole attribution — which is why file marks are studied so closely on shortened (o-suriage) swords that lost their original signature.
Buyer's angle: yasurime and fakes
Because the nakago and its yasurime are where a forger's work is most exposed, they are a core check when buying an antique Japanese sword:
- Freshly cut marks on an old tang. On a genuine antique the yasurime are aged and darkened along with the rest of the patina. Bright, sharp new filing on a supposedly old nakago is a red flag for a re-cut tang or a false signature.
- File marks that disagree with the signature. If the pattern is wrong for the smith named in the mei, the signature is suspect — a classic gimei (false signature) tell.
- Filing that cuts through the patina or the mei. Yasurime should sit under the aged surface, not through it; recent filing over old rust points to tampering.
- Papers. When authenticity turns on such details, a certificate from a body like the NBTHK, whose appraisers read the yasurime directly, is worth far more than a seller's word.
Frequently asked questions
What are yasurime on a Japanese sword?
Yasurime (鑢目) are the file marks a swordsmith cuts into the tang, or nakago, of a Japanese sword. They help grip the handle, but because the tang is never polished they survive as a signature clue — their direction and style help experts attribute a blade and test whether its signature is genuine.
What are the main yasurime patterns?
Common patterns include kiri (horizontal), sujikai (diagonal slant), katte-sagari (a gentle downward slant), o-sujikai (steep slant), higaki (cross-hatched lattice), and kesho (decorative border filing). Particular patterns are associated with particular schools and periods, which helps narrow an attribution.
Why do yasurime matter for authentication?
Because the tang is left unpolished, yasurime preserve the smith's original hand and habits. Appraisers check whether the filing is consistent with the claimed smith and with the signature above it, and freshly cut marks on an otherwise old tang are a warning sign of a re-cut tang or a false signature.
Can yasurime reveal a fake signature?
Often, yes. If the file marks do not match the pattern a smith habitually used, or if bright new filing appears on an aged tang, the signature is suspect. Yasurime are one of the details forgers most frequently get wrong, so they are a key check in kantei.
Keep exploring nihonto
- Nakago — the tang that carries the yasurime.
- Mei — the signature read alongside the file marks.
- Kantei — how experts appraise and attribute a blade.
- Mei Reader — decode a signature on a tang.
- Japanese Sword Glossary — browse every nihonto term.