Nakago-jiri Shapes and Finishing: How Kuri-jiri, Ken-gata, and Iriyama-gata Reveal a Smith's Aesthetic
* Image is for illustrative purposes only.Table of Contents
The Method Dwelling in the "End" of the Tang
The part of a Japanese sword that fits into the grip (tsuka), namely the nakago, normally remains hidden within the scabbard and grip, out of view. However, in sword authentication (kantei), the nakago is the most important source of information for determining the maker and period. The end of the nakago, the tip on the opposite side of the blade, is called the nakagojiri, and its shape reveals the sword maker's method and aesthetic sense.
The nakagojiri, along with the mekugi-ana (peg hole), mei (signature), and yasurime (file marks), is an indispensable part when discussing the sword.
Main Forms of the Nakagojiri
The nakagojiri has several standard forms, each with its own name. Here are the representative ones.
| Name | Characteristics |
|---|---|
| kurijiri | A rounded form like a chestnut, said to be the most common nakagojiri |
| kengyo | Sharpened from both sides and formed like a sword point |
| iriyamagata | A form where the angle differs between the spine side and blade side, asymmetrically arranged as if a mountain were set inward, commonly seen in certain schools |
| ichimonji | Cut straight |
These forms are not mere decoration but reflect the sword maker's lineage and period preferences. For example, the iriyamagata is said to be common in Mino-school swords, and clues about the maker can sometimes be obtained from the form of the nakagojiri.
The Technique of Forming the Nakagojiri
The shaping of the nakagojiri is done in the nakago finishing process after hardening. The sword maker uses yasuri (files) and tagane (chisels) to shape the end according to the standard form. Subtle variations in roundness and angle reveal individual sword maker's habits.
Unlike the blade, the nakago is not polished and refined, and the traces of the hammer and file from creation, as well as the grain of the forged iron, remain intact. Therefore, the care in forming the nakagojiri and the peculiarities in its shape are transmitted unchanged to later generations, serving as reliable evidence for identifying the maker.
Kesho-Yasuri—Decorative File Marks on the Nakago
On the surface of the nakago, the sword maker engraves marks called yasurime (file marks) with a file. This serves both a practical purpose of increasing friction between the nakago and grip to aid fastening, and carries a meaning like the sword maker's signature. Yasurime comes in many types, such as sujikaI (diagonal lines), kattesagari (offset descending lines), and higaki (bamboo fence pattern), and each school has its own characteristics.
Among these file marks, those decoratively applied near the nakagojiri or along the edges of the nakago are called kesho-yasuri (decorative file marks). In addition to the original yasurime, short decorative file marks are added to the upper part of the nakago for appearance, and these are frequently seen on swords from the Shinto period onward. The presence or absence of kesho-yasuri and how they are applied also serve as clues for determining the period and maker.
Suriage and Nakagojiri—When Form Is Lost
What should be noted is that the form of the nakagojiri is not always preserved in its original state from creation. When suriage (shortening), the process of reducing the blade's length, is performed in later generations, the nakago is cut and shortened from its end, and the original form of the nakagojiri is lost. Those greatly sanded down with the signature area lost are called o-suriage mumeisho, and many older tachi made in extended length are found in this condition.
In other words, the standard form of the nakagojiri remains intact only in ubu nakago, the nakago that remains in its original as-made state. When observing the nakago, the first step is to distinguish between ubu and suriage. Whether suriage has been performed is determined comprehensively from the number and position of mekugi-ana, the way yasurime patterns are interrupted, differences in rust color on the nakago, and other factors.
Practical Checklist for Nakago Observation
Let us organize the procedure when actually observing the nakago.
- First, the overall form. Is it ubu or suriage? How many mekugi-ana are there? If there are multiple mekugi-ana, it may indicate evidence of grip replacement or suriage.
- Second, the form of the nakagojiri. Is it kurijiri, kengyo, iriyamagata, or ichimonji? Observe down to the subtle habits in roundness and angle.
- Third, the yasurime. The type—sujikaI, kattesagari, higaki, and others—and the presence or absence of kesho-yasuri.
- Fourth, the color of rust. The rust on the nakago is said to deepen and settle in tone as time passes, and it is used as a reference in authentication, but since judging rust color requires experience, it is safer to refrain from making definitive statements.
- Fifth, the mei (signature). If present, observe the script style, position, and technique of the chisel work. Since there is always the possibility that the signature was cut as a forgery in later periods, it is essential to examine it in consistency with the overall finishing of the entire nakago.
What Not to Do—Rust on the Nakago Is Historical Data
What must be absolutely avoided in handling the nakago is removing the rust. The rust and yasurime on the nakago are primary sources containing information spanning hundreds of years, and if polished or washed with chemicals, that information can never be recovered. In authentication, traces of work done on the nakago are considered a significant negative factor. Maintenance should be limited to the blade, and the nakago should only be lightly wiped with a dry soft cloth.
The Hidden Part Speaks Eloquently
The nakagojiri and kesho-yasuri are modest parts compared to the showy hamon and jihada of the blade. However, precisely because they are hidden in the grip and out of public view, they are less likely to be altered, and faithfully preserve the traces of the sword maker's hand from the time of creation. This is why authenticators place such importance on the nakago.
If you have the opportunity to hold a sword, I encourage you to also pay attention to the form of the nakagojiri and the lines of the file marks. The roundness of the kurijiri, the angles of the iriyamagata, the fine lines of the kesho-yasuri—in each of these, the method of the craftsman who made the sword and the aesthetic sense of the era are quietly inscribed.
Touching the Making of Swords
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