Parts of a Japanese Sword: The Complete Anatomy Guide

The first time a serious buyer asks us about a blade, the questions are almost always in the wrong vocabulary. People ask about "the handle" and "the blade pattern" when they mean the tsuka, the hamon, and the hada. That gap is not just cosmetic. When you cannot name a part precisely, you cannot ask the question that protects you, and you cannot follow the answer a dealer gives. This guide fixes that. Every term here maps to a feature that affects authenticity, attribution, or price.

Why the Vocabulary Matters Before You Buy

Japanese sword scholarship has a precise vocabulary for a reason. A blade is attributed to a smith, school, and period based on the combination of dozens of physical features, and each feature has a name. When an NBTHK certificate attributes a blade, it is reading the sugata (overall shape), the hamon (temper line), the hada (grain), the boshi (tip temper), and the nakago (tang) as a single coherent signature of a workshop and era. If you want to understand what you are buying, you need the same words the examiners use.

There is also a practical defense in it. The most common way buyers overpay is by accepting a vague description. "Antique katana, beautiful temper line" tells you nothing verifiable. "Suguha hamon in nie-deki, ko-itame hada, ubu nakago with two mekugi-ana and a clear mei" tells you exactly what to check. The vocabulary is the difference between a description you can verify and a sales pitch you have to trust.

The Three Sections of a Nihonto

A complete Japanese sword separates into three parts, and they are almost always discussed separately because they are valued separately.

The blade is the steel itself: the cutting body, from the point to the end of the tang. The nakago is the tang, the unpolished lower portion of the blade that sits hidden inside the handle and carries the signature. The koshirae is the full set of mountings: handle, guard, scabbard, and the metal fittings that decorate and secure them. A blade can be sold in koshirae (full mounting) or in shirasaya (a plain wooden storage scabbard), and the two are different objects commercially. We cover that distinction in our guide to koshirae versus shirasaya.

Parts of the Blade

The blade is described from the point downward. These are the terms you will see in every dealer listing and every certificate.

Two of these deserve special attention because they carry information that anchors a blade in time. The sori (curvature) is one of the most reliable period indicators on the entire sword. Deeply curved blades with the deepest point near the handle (koshi-zori) point toward early work; shallower, more even curves point toward later eras. The kissaki tells a similar story: compact, small points are typical of certain early production, while elongated points are associated with specific later periods and schools. A blade whose sori and kissaki contradict its claimed period is a blade worth questioning.

Surface Features: Hamon, Hada, and Hataraki

The visible surface of a polished blade is where the forging reveals itself, and where most of a connoisseur's attention goes. These features cannot be reproduced by stamping, casting, or machine grinding, which is why they are central to telling genuine nihonto from replicas.

Hamon (刃文) is the temper line: the bright, often wavy boundary along the edge created by differential hardening with a clay coating before quenching. The hamon's pattern (straight suguha, irregular midare, undulating gunome, and many named variants) is a fingerprint of the smith and school. Our full breakdown of how to read the hamon covers this in depth.

Hada (肌) is the grain pattern of the steel, the visible result of folding the tamahagane during forging. Wood-grain itame, straight masame, and burl-like mokume are the broad categories, and each tradition favored particular hada. We explain it fully in our guide to jihada and the grain pattern.

Hataraki (働き) means "activity": the fine metallurgical phenomena within and around the hamon, such as nie (bright individual crystals), nioi (a misty band of finer crystals), kinsuji, and sunagashi. These are the details that separate a workmanlike blade from a masterpiece, and they are nearly impossible to fake because they are a byproduct of how the steel actually crystallized during quenching. The boshi (帽子), the hamon as it turns through the kissaki, is the single feature forgers most often get wrong.

The Nakago: Where Authentication Happens

If you remember one part from this guide, make it the nakago. The nakago is the tang, the unpolished extension of the blade that sits inside the handle. It is the most important part of the sword for authentication, and it is the part most buyers never look at properly because it is hidden during normal handling.

The nakago carries several pieces of evidence at once. The yasurime (鑢目) are the file marks the smith cut into the tang, and their pattern is characteristic of specific smiths and schools. The mekugi-ana (目釘穴) are the holes drilled for the bamboo peg that holds the blade in the handle; the number and placement can indicate whether a blade has been shortened. The patina, the deep, even rust of age on the nakago, takes centuries to form and is extremely difficult to fake convincingly. And the mei (銘), the signature chiseled into the tang, names the smith when present.

The nakago also tells you whether a blade is ubu (unaltered, original length) or suriage (shortened, usually to convert an older tachi to katana length). A shortened blade may have lost its original signature, which has major consequences for attribution and value. We cover this in detail in ubu nakago versus suriage. A signature is not automatically good news either: false signatures (gimei) were added throughout history to inflate value, which is why reading the mei correctly is its own skill, covered in our guide to reading the mei.

The reason examiners trust the nakago over the blade surface is simple: the blade gets polished, sometimes repeatedly across centuries, which gradually changes the surface. The nakago is never polished. It is preserved exactly as the smith left it, minus the patina of age. That makes it the most honest part of the sword.

Parts of the Mounting (Koshirae)

The koshirae is the assembled mounting, and it is a craft tradition in its own right. The metal fittings were often made by specialist artisans, and a fine koshirae can carry significant value independent of the blade. The main components:

The tsuba, fuchi, kashira, and menuki together are called the toso-gu, the soft-metal fittings, and collecting them is a discipline of its own. A blade can wear a koshirae that is far older or far more valuable than the blade itself, or a modern set commissioned to display an antique blade properly. We explain how mountings are valued in our guide to the art of koshirae.

Which Parts Decide Value

Not every part carries equal weight when a blade is priced. In rough order of impact for a collectible antique nihonto:

• The nakago and mei drive attribution, and attribution drives value more than anything else. A confirmed signature from a sought-after smith can multiply a blade's price several times over.
• The hamon, hada, and hataraki determine artistic quality within an attribution. Two blades by the same school can differ in price substantially based on the refinement of these features.
• Condition of the blade surface, including whether it is in good polish and free of fatal flaws, sets a ceiling on value regardless of attribution.
• Sugata, sori, and kissaki confirm period consistency. A coherent shape supports the attribution; an inconsistent one undermines it.
• The koshirae adds value, sometimes considerable, but is generally secondary to the blade unless the fittings are themselves important works.

This is why a credible NBTHK certificate matters so much: it is a professional reading of all these parts at once, made in person by examiners who handle nothing but nihonto. If you are new to certification, start with our NBTHK certificate guide.

Frequently Asked Questions

What are the main parts of a Japanese sword?

Three sections: the blade (the visible steel, including the kissaki tip, the ha edge, the shinogi ridge, and the surface where hamon and hada appear), the nakago (the tang inside the handle, carrying the mei signature), and the koshirae (the mounting: tsuka, tsuba, fuchi, kashira, menuki, and saya).

What is the most important part for authentication?

The nakago. Its shape, file marks (yasurime), patina, and signature are the primary evidence used to attribute a blade. Because the nakago is never polished, it preserves the smith's original work and is harder to fake than the blade surface.

What is the curved tip of a katana called?

The kissaki, the hardened point bounded by the yokote line. The hamon as it passes through the kissaki is the boshi, a feature forgers frequently get wrong, which makes it a useful authenticity check.

What is the difference between the hamon and the hada?

The hamon is the hardened temper line near the edge, created by differential clay hardening. The hada is the grain pattern of the folded steel across the blade surface. Both are products of traditional forging and are central to identifying genuine nihonto.

Do katana, wakizashi, and tanto use different part names?

No. The vocabulary is identical across all nihonto. They differ by blade length category, not by the names of their parts, so kissaki, hamon, nakago, and mei apply to all three.

Key Takeaways

• A nihonto is described in three sections: the blade, the nakago (tang), and the koshirae (mounting), each valued separately.
• The nakago is the most important part for authentication, because its shape, file marks, patina, and mei are rarely altered and carry the evidence of attribution.
• Surface features (hamon, hada, hataraki) reveal the forging and cannot be reproduced by machine, making them central to telling genuine nihonto from replicas.
• Sori and kissaki are reliable period indicators; a shape that contradicts a claimed period is a red flag.
• The koshirae can hold significant value on its own, but the blade and its attribution drive the price.

Once you can name the parts, you can read a listing critically and ask the questions that protect you. If you want to apply this to a real blade, browse our collection of authentic Japanese katana, where every piece is described with this exact vocabulary, or contact us directly with a blade you are evaluating. By the Tokyo Nihonto Team, sourced directly from Japan.