Reading the Nakago — What Inscriptions and File Marks Reveal

What is Nakago?

Nakago (the tang) is the part of the blade that fits into the handle, and is the most important source of information about a sword. While attention is often drawn to the elaborate hamon (blade pattern) and jihada (surface texture) of the blade, it is the nakago that can be called the sword's "résumé." The sword smith's signature, the era of creation, characteristics of the school, and traces of later modifications are all recorded here. In the world of appraisal, it is said to be such an important location that "if you understand the nakago, you understand the sword."

Reading the Smith and Era from the Signature

The mei (signature) is the sword smith's signature. The omote-mei (front signature) is engraved with the smith's name, while the ura-mei (back signature) may contain the year of production, the patron's name, and the place of manufacture. The authenticity of the sword and its estimated era are determined by the presence or absence of the signature and the way it is written.

The famous sword smiths of the Koto (old sword) period each cut well-known signatures. For example, signatures such as "Osafune" from Bizen Osafune and "Awatabugi" from Yamashiro Awatabugi represent the highest level of their respective eras. On the other hand, many unsigned blades exist, especially among older swords and those heavily used on the battlefield. The era and school can also be estimated from the script of the signature and the depth of the carving.

Understanding the Smith's Individuality from the File Marks

Yasuri-me (file marks) are the direction and shape of file marks applied to the nakago. The file marks left on the original tang are like fingerprints, revealing the smith's habits and technical skill.

The main types of file marks are as follows:

• Kiri (straight): File marks drawn in a straight line from top to bottom. A simple, craftsman-like finish.
• Katte-sagari (diagonal): File marks drawn diagonally from upper right to lower left. The most common type, used by many schools.
• Suji-chigai (reverse diagonal): File marks drawn from upper left to lower right, the opposite direction of katte-sagari. It can be characteristic of specific schools.
• Higaki (lattice): Complex file marks crossing in a lattice pattern, requiring advanced technique. Seen in higher-ranking smiths such as those of the Soshu tradition.

File marks are the most important clue in determining authenticity. Original file marks on old swords show natural wear, which is proof of authenticity. Forgeries have unnatural file marks, often carved with uniform pressure throughout, and can be detected by experienced appraisers.

What Patina Color Reveals About Age

Sabi-iro (patina color) refers to the color and texture of rust that has accumulated on the nakago. Old tangs have deep natural black patina, and this "aged appearance" indicates the depth of time.

The following can be read from the patina color:

• Deep black patina: Indicates the passage of several hundred years or more. The steel's oxidation has progressed deeply.
• Brown patina: Commonly seen on swords from the middle to late Edo period.
• Light patina: Seen on relatively new swords or those in good condition.

Attempts are sometimes made to artificially age the patina, but natural rust has subtle variations in tone and texture that experts can discern. The depth and quality of patina can also be confirmed through scientific analysis.

What Repolishing Tells About a Sword's Life

Suriage (shortening) refers to the state in which the nakago has been cut short to shorten the blade. This is not damage or a defect, but rather indicates a practical modification of the sword.

• Ubu-nakago (original tang): The state in which it remains unchanged from the time of creation. The signature is completely preserved, making era determination accurate.
• Suriage: The upper part has been cut. Part of the signature may remain, or a cut signature may be inlaid as a "gaku-mei" (framed signature).
• Ō-suriage (major repolishing): Extensively cut with the signature completely lost. Often seen in examples where large tachi from the Namboku-cho period were converted to shorter katana during the Edo period.

Repolishing reflects the demands of its era. The long tachi from the Namboku-cho period were remade into more maneuverable katana when arquebuses became widespread during the Sengoku period. This modification is not forgery, but rather important evidence of the sword's historical evolution.

Mastering the Art of Reading the Nakago

Correctly reading the nakago is the foundation of appraisal. By comprehensively observing the signature, file marks, patina color, and condition of repolishing, the sword's provenance becomes clear. Deciphering a single character of the signature can change the sword's era, and a single file mark can lead to identifying the school—once you experience the fascination of such appraisal, your way of viewing swords changes fundamentally. The nakago is a sword's résumé, a silent message sent by the smith to future generations. Please practice with actual swords.