Nakago and Tang Inscription — Stylistic Evolution Through the Ages

Structure and Function of the Nakago

The nakago (tang) is the extension of the blade that is concealed within the hilt (tsuka) — the equivalent of the "tang" in Western sword terminology. It maintains the structural integrity of the sword as a whole while forming the junction with the hilt. The principal parts of the nakago are as follows:

- **Mune**: the ridgeline along the spine side of the nakago - **Hamoto**: the edge on the blade side - **Nakago-ana**: the hole through which the mekugi (retaining peg) passes; multiple holes indicate suriage (shortening) - **Nakago-jiri (saki)**: the tip of the nakago; its shape varies by period (kurijiri, kenkata, ha-agari kurijiri, etc.) - **Yasurime**: the file-mark pattern on the nakago surface; the direction and coarseness of file marks indicate school and period characteristics - **Mei**: the inscribed text (smith's name, date, province, dedication, etc.)

The nakago is formed from the same iron as the blade body, but unlike the blade it is not hardened (quenched), remaining in its untempered state. As a result, the nakago is susceptible to rusting and develops a characteristic patina over time. The condition of this rust provides vital evidence for estimating the date of manufacture.

Stylistic Evolution of Nakago Inscriptions

The practice of inscribing Japanese swords is believed to have begun in the late Heian period (approximately 11th–12th centuries). Early inscriptions were simple, consisting of little more than the smith's name, but over time they came to convey a wider range of information.

**Heian–Kamakura Period**: Inscriptions were generally brief — typically a smith's name or a short phrase such as "made by ___." They were most commonly engraved on the mune side of the omote (the face visible when the sword is worn edge-upward). From the mid-Kamakura period onward, as outstanding smiths rose to prominence, the inscription began to function as an authentication of the sword's value.

**Nanbokuchō–Muromachi Period**: During the era of mass sword production, swords both with and without inscriptions circulated. Large great swords and nodachi sometimes bear lengthy dedicatory inscriptions. This is also the era when nagamei (long inscriptions containing the smith's name, province, and date in extended form) became common.

**Momoyama–Early Edo Period (Shintō Era)**: The style of inscriptions underwent significant change from the Shintō period onward. Reflecting heightened self-consciousness among smiths, it became standard to record province, location, and date in detail. Individual calligraphic styles developed distinctively for each smith.

**Mid–Late Edo Period (Shinshintō Era)**: Shinshintō smiths engaged in deep study of kotō (classical sword) styles and increasingly evoked archaic inscription conventions. Some declared their work "copies" (utsushi) or "imitations" (narai) and reproduced the inscription style of classical-period masters — a matter requiring close attention in authentication.

**Meiji Onward**: As sword production became confined to the domain of fine art and craft, inscriptions took on greater significance as artistic signatures. Many modern smiths combine the standard formula of province, location, and date with a personal seal or cipher.

Periodic Changes in Nakago Shape

The shape of the nakago exhibits characteristic changes over time.

- **Kotō Period (through 16th century)**: The nakago-jiri (tip) in the dominant "kurijiri" (chestnut-bottom) rounded form. Tachi tangs are slender and long, and more curved than those of uchigatana. - **Shintō Period (17th century onward)**: Nakago-jiri shapes diversify, with "kenkata" (sword-shaped) and "ha-agari kurijiri" (edge-rising chestnut) appearing. The spread of the uchigatana altered the length and thickness of the nakago. - **Shinshintō Period (late 18th century onward)**: A tendency to consciously reconstruct the nakago shapes of kotō appears; however, subtle differences from genuine kotō shapes often remain, providing evidence for appraisal.

Classification and Significance of Yasurime

Yasurime (file marks) are the patterns left on the nakago surface during the finishing process. These patterns differ by school and period and constitute an important criterion for appraisal.

Principal types of yasurime: - **Kiri (cut)**: horizontal file strokes - **Sujihai (diagonal)**: angled file strokes - **Higaki (cypress-fence)**: crosshatch pattern (diamond shapes) - **Ōsujihai (large diagonal)**: broadly angled file strokes - **Kesho (cosmetic)**: fine finishing file marks

Bizen school works, for example, characteristically display kiri yasurime, while Sōshū school works more often show sujihai. Because these tendencies also vary by period and individual, appraisal requires integrating multiple elements rather than relying on any single feature.

Shinmei, Kin-zōgan-mei, and Orikaeshi-mei

Beyond the authentic inscription (shinmei — inscribed by the smith in person), several specialized inscription forms exist.

**Kin-zōgan-mei (gold inlay inscription)**: When later appraisers (such as the Hon'ami family) attributed an unsigned blade to a specific smith, they recorded their judgment by inlaying gold into the nakago. Known as "Hon'ami kiwame," this form carries great authority and is highly regarded today.

**Orikaeshi-mei (folded inscription)**: When a blade was shortened (suriage), the section bearing the original inscription was sometimes folded over and preserved inside the hilt area. If the hilt is removed, the original inscription may be visible.

The ability to accurately distinguish these inscription forms is an indispensable skill in Japanese sword appraisal.