Essential Component of the Japanese Katana Sword: The Nakago (Tang)

Nakago (Tang)

The nakago, also known as the “center,” is the part of a Japanese katana that contains the richest information for authentication purposes, and its importance is on par with that of the blade itself. When appreciating Japanese swords, beginners typically focus more on the mountings (koshirae), intermediate enthusiasts pay closer attention to the blade geometry (sugata), while the most advanced collectors place particular emphasis on the information conveyed by the nakago. However, many observers fixate solely on the signature (mei), which leads them into a common misconception. In reality, signatures can be genuine or forged, and accurate authentication requires a comprehensive evaluation that incorporates other characteristics of the nakago. Authentication can be approached from the following aspects:

1. Types of Nakago (Tang Shapes)

Different tang shapes reflect traditional schools, eras, and stylistic preferences of Japanese swordsmiths. Below are the major forms:

• Kiri-nakago

Straight-cut tang.

• Takayama-kei nakago

Tang in the Takayama style.

• Ken-gata nakago

Sword-shaped tang with a straight, tapered silhouette.

• Shibuhara nakago / Shibu-hara gata

Carp-belly tang with a gently rounded profile.

• Funagata nakago / Funa-gata

Boat-shaped tang reminiscent of a ship’s keel.

• Furisode-gata nakago

“Furisode” sleeve-like tang with an elegant outward flare.

• Sen-gata nakago

Coin-shaped tang end or rounded disc-like form.

• Kijimomo-gata nakago

“Pheasant-thigh” tang, a distinctive shape with swelling near the middle.

These forms are essential clues for identifying the sword’s lineage and authenticity.

Shape

The shapes of nakago include kirijiri (cut-off end), takahagire (high-traveling style), funagata (boat-shaped), kijimomo (pheasant-thigh shaped), furisode (swinging-sleeve style), koifukura (carp-belly shaped), tsurugi-gata (sword-pointed), among others. Even within the same nakago type, the shape of the base (nakago-jiri) may vary. Generally, an individual smith maintains a consistent nakago form throughout their career. Thus, the external shape of the nakago serves as a crucial reference point in authentication. Counterfeit swords sometimes feature unusual or inconsistent nakago shapes.

2. Nakago-jiri: Tang-End Shapes

The shape of the tang end, or nakago-jiri, is a key feature in Japanese sword appraisal. Each type indicates certain schools or periods.

• Kiri-jiri

Straight-cut tang end.

• Kuri-jiri

Chestnut-shaped tang end, one of the most common forms.

• Ha-agari Kuri-jiri

Chestnut-shaped tang end raised toward the blade edge.

• Ken-gata jiri

Sword-point shaped tang end.

• Iriyama-gata jiri

Inverted mountain-shaped / V-shaped tang end.

• Saki Kuri-jiri

Slender, forward-leaning chestnut-shaped tang end.

• Katakiri-jiri

One-side beveled tang end.

Nakago-jiri is often enough to identify the school or tsukurikomi style even without viewing the whole blade.

Nakago-jiri (Tang Tip)

Located at the base of the nakago, the nakago-jiri comes in various forms that reflect the traits of specific schools and individual smiths. Common shapes include nyūyama (mountain-entry), tsurugi (sword-pointed), kiri (straight-cut), kurijiri (chestnut-shaped), hasuji-kurijiri (edge-aligned chestnut), saki-kurijiri (front chestnut), and katashō (single-beveled).

Yasurime (File Marks)

Beyond its overall shape, a smith often files distinctive patterns onto the nakago. These patterns, called yasurime, increase friction between the tang and handle (tsuka), preventing slippage. Basic yasurime types include katchōshita (victorious upper hand), kiri (straight filing), katchōue (victorious lower hand), sujikai (diagonal lines), ō-sujikai (broad diagonal lines), hinokigaki (cypress fence), takaba (hawk feather), gyaku-takaba (reverse hawk feather), kiri-sujikai (combined straight and diagonal), and senzuki (hoe-shaped). These patterns can be freely combined into what is known as keshō-yasuri (“decorative filing”), yielding countless variations. Yasurime conveys information about a sword’s school or lineage—each pattern is typically associated with a specific school or family. If the signature (mei) is likened to a smith’s handwritten signature, then the yasurime is equivalent to their fingerprint.

3. Yasurime: Types of File Marks

File marks (yasurime) are intentionally applied to increase friction for the sword handle and serve as a signature of the smith or school. Each pattern is highly distinctive:

• Katte-agari yasurime

Upward-slanting file marks.

• Kiri yasurime

Straight horizontal file marks.

• Katte-sagari yasurime

Downward-slanting file marks; commonly used in Mino tradition.

• Suji-chigai yasurime

Fine cross-hatched pattern.

• Ō-suji-chigai yasurime

Large, bold cross-hatched pattern.

• Hinoki-gata yasurime / Hinoki yasurime

Grid-like marks resembling hinoki wood latticework.

• Taka-no-ha yasurime

“Hawk feather” patterned file marks.

• Kiri-suji-chigai yasurime

Hybrid pattern combining horizontal and diagonal cross-hatching.

• Kuwa-kogi yasurime

Hoe-shaped pattern with distinctive scraping strokes.

Because yasurime can be extremely difficult to forge convincingly, they are among the best indicators for detecting fake or altered tangs.

Rust Patina

A well-preserved, aged Japanese sword typically exhibits a blade that remains bright and freshly polished, whereas the nakago almost always shows signs of rust. This occurs for two main reasons: first, the steel of the nakago is not hardened through quenching; second, the maintenance methods for the blade and nakago differ significantly. The blade is regularly cleaned and treated with specialized polishing powder (uchiko) and oil, while the nakago is generally left to develop natural rust over time. After centuries, this results in a dense, black patina that acts as a protective layer against further oxidation.

With modern techniques, forging rust patina is relatively easy—chemical oxidizers can be applied to produce the appearance of a thousand-year-old nakago overnight. However, such fakes are easily detected by experts: artificially induced rust appears duller, and rubbing it with a finger will transfer loose surface rust (ukisabi).

Newly made swords (shinsakutō) have nakago in bare metal, showing no rust whatsoever.

Mekugi-ana (Peg Hole)

Also called mekugi-ana (“peg hole”), the hole used to secure the mekugi (retaining peg) is not perfectly cylindrical—it is slightly tapered, being wider on one side and narrower on the other. Consequently, the peg hole itself mirrors this asymmetry, with one opening larger than the opposite. Swords that have been remounted or modified often possess two or more mekugi-ana.

In contrast, modern reproductions drilled with precision machinery typically feature overly perfect, uniformly round holes.

Mei (Signature)

Smith Signatures: Upon beginning their craft, Japanese swordsmiths adopt a professional name (kōmyō) used as their artistic signature (mei) on blades—similar to a stage name for performers or a pen name for authors. For example, in the name “Haruaki Akishige,” “Haruaki” is the family name, “Akishige” is the smith name, and his birth name was Hikosaburō. Smith names follow standardized conventions, usually consisting of two kanji characters drawn from recurring elements such as “Tada-” (loyal), “Kuni-” (province/country), “Kane-” (combine), and “Yoshi-” (fortunate).

The mei is the most conspicuous feature on the nakago, precisely because of its visibility, it is also the most frequently forged—thus, its evidentiary value is often less reliable than other features. A single smith may use different signatures during different periods, and conversely, identical signatures may appear across unrelated eras.

The two sides of the nakago are designated omote (front) and ura (back). When the sword is placed with the point facing away and the cutting edge to the left, the upward-facing side is the omote, and the reverse is the ura. On katana, wakizashi, and tantō, the smith’s name is typically inscribed on the omote, while the date or era appears on the ura. For tachi, the convention is reversed. However, certain schools occasionally deviate from this norm.

Signatures are categorized as either short (tanmei) or long (chōmei). Short signatures usually consist only of the smith’s name—e.g., Masamune, Yoshimitsu, Muramasa, Sadamune—with the briefest examples containing just a single character, such as “Sō” (also called Sō-moji) or “Ichi” (Ichi-moji). Long signatures include additional information preceding the name, such as province and honorary title—for instance, “Hizen no Kuni Jū Mutsu no Kami Tadayoshi” (“Resident of Hizen Province, Mutsu no Kami Tadayoshi”), where “Hizen” denotes the region, “Mutsu no Kami” is a court title, and “Tadayoshi” is the smith’s name. Some signatures even record supplementary details like the smith’s age, owner’s name, or test-cutting results; those including test-cut data are called saidan-mei (“test-cut signatures”). Short signatures predominated during the kotō (ancient sword) period, while long signatures became increasingly common in the shintō (new sword) era.

Certain mei were passed down through generations within a family—for example, by the Meiji period, the name “Kaneie” had been inherited by 23 successive smiths, and “Izumi no Kami Kaneshige” reached its 11th generation. Such signatures functioned much like registered trademarks for family-run enterprises.

Within the same school, smiths often share a common character in their names. For instance, in the Bizen Osafune school, the second character is frequently “Mitsu” (光)—e.g., Tadamitsu, Kagimitsu, Kiyomitsu, Yasumitsu; in the Mino Seki school, the first character is commonly “Kane” (兼)—e.g., Kanehira, Kaneie, Kaneshige, Kanekuni; and in the Gassan school, the first character is “Sadame” (貞)—e.g., Sadame, Sadakatsu, Sadayoshi, Sadatoshi.

Forged signatures are known as gimei. The more renowned the smith, the more prevalent the forgeries. Distinguishing genuine from fake signatures is among the most challenging tasks in sword appraisal—akin to authenticating classical Chinese calligraphy—and requires decades of accumulated expertise.

Some swords bear no signature at all; these are called mumei (“unsigned”). Common reasons for absence of a mei include: apprentices who had not yet graduated to independent smithing did not sign their work; blades commissioned by daimyō (feudal lords) for presentation to shoguns or temples were often left unsigned; and smiths sometimes chose not to sign blades they deemed unsatisfactory. Therefore, an unsigned sword is not necessarily inferior—it must be judged holistically based on its intrinsic qualities. When authenticated by authoritative experts, the verdict may be inscribed onto the nakago using cinnabar lacquer, known as shu-mei (“vermilion signature”), or inlaid in gold, called kin-zōgan mei (“gold-inlaid signature”).

Occasionally, a signature needs correction. In such cases, the erroneous portion is carefully chiseled out and replaced with a new piece of steel bearing the corrected inscription—a technique known as gaku-mei (“inset signature”).

Suriage (Shortening)

During a sword’s service life, it might be shortened for various reasons—such as changing mountings, change of ownership, or shifts in combat tactics. This process, called suriage, involves cutting off part or all of the original nakago and reshaping the end of the blade body (through filing or grinding) to form a new nakago. When the entire original nakago—and sometimes even part of the blade—is removed, it is termed ō-suriage (“major shortening”). In contrast, an untouched, unmodified nakago is called ubu-nakago (“original tang”). Because the newly formed nakago originates from the hardened portion of the blade, its rust characteristics differ from those of an ubu-nakago, often exhibiting more noticeable surface rust (ukisabi). During shortening, part or all of the original signature may be lost; typically, no new signature is added afterward, rendering the sword mumei. In some cases, the unsigned side of the nakago is thinned by half and folded over so the signature transfers from one face to the other—a method known as orikaeshi-mei (“folded-back signature”).

4. Suriage: Types of Tang Shortening

Throughout history, swords were often resized due to changes in fighting style, mounting requirements, or fashion. These modifications are collectively called suriage.

• Ori-kaeshi Nakago

Folded-back tang.
A section of the original tang (including the mei) is cut off, thinned, folded back, and reattached so that the signature is preserved.

• Kuri-sage (Machi-okuri)

Lowered machi / machi-shifted tang.
The blade is shortened by moving the machi forward without cutting the tang itself.

• Ō-suriage Nakago

Greatly shortened tang.
The tang is cut back extensively, usually eliminating the original signature. Very common in early blades (kotō).

• Suriage Nakago

Standard shortened tang.
Moderate reduction; sometimes retains partial original form.

• Ubu Nakago

Unaltered, original tang.
Completely untouched since creation, retaining the original patina, mei, and mekugi-ana. Highly prized by collectors.

Final Collector’s Note​

The nakago isn’t just a “stick” at the end of the blade—it’s a timeline, a signature, and a lie detector. As an navigating this Japanese art form, I’ve learned that authentication is about pattern recognition: shape + yasurime + patina + mekugi-ana must align. Ignore the flashy koshirae or bold mei—look to the nakago. It never lies.​

Next time you’re inspecting a sword, run your finger along the yasurime, check the mekugi-ana taper, and study the nakago-jiri. You’ll be surprised how quickly you separate genuine works from overpriced fakes.