Introduction

The nakago (茎) is the tang of a Japanese sword (nihontō, 日本刀)—the unsharpened portion of the blade that extends into the hilt (tsuka, 柄). While not visible when the sword is mounted, the nakago is an essential part of the sword’s functionality, balance, and historical identity.

The nakago’s shape, finish, and inscriptions provide valuable information about the sword, including its age, the school of forging, and the signature (mei, 銘) of the swordsmith. Additionally, the unique filing patterns (yasurimei, 鑢目) and tang tip shapes (nakago-jiri, 茎尻) serve both practical and aesthetic purposes.

This guide explores the function, anatomy, and extensive variations of nakago, nakago-jiri, and yasurimei, along with their significance in traditional Japanese swordsmithing.

The Function and Importance of the Nakago

The nakago serves several crucial roles in the construction and use of a Japanese sword:

  1. Securing the Blade to the Handle
    • The nakago is inserted into the tsuka (hilt) and secured with a bamboo peg (mekugi, 目釘).
    • A well-shaped nakago ensures a tight and stable fit, preventing the blade from loosening.
  2. Balancing the Sword
    • The length, thickness, and shape of the nakago directly affect the weight distribution of the sword.
    • Longer nakago provide better leverage for two-handed swords like tachi and katana.
  3. Preserving the Swordsmith’s Signature (Mei, 銘)
    • Many swordsmiths engrave their mei (signature) on the nakago, often alongside dates and inscriptions.
    • The mei is a key factor in identifying authentic swords and determining their value.
  4. Historical Authentication
    • Nakago shape and file marks provide clues about the sword’s time period, school, and forging techniques.
    • Certain patterns and styles are associated with specific swordsmiths and regions.
  5. Preventing Corrosion
    • The nakago is left unpolished and develops a natural rust patina, which helps prevent deeper corrosion.

Types of Nakago-jiri Shapes (茎尻, Tang Tip Styles)

The nakago-jiri refers to the specific shaping of the tang’s end. Each variation reflects different smithing traditions and periods.

1. Ha-agari Kurijiri (刃上がり栗尻) – “Rounded Chestnut Shape with Raised Edge”

  • The tang has a rounded end with a slightly raised ridge on the cutting edge side.
  • Common in Muromachi and Edo period katana.

2. Kuri-jiri (栗尻) – “Chestnut Shape”

  • The nakago tapers to a smooth, rounded end, resembling a chestnut.
  • Often found in Soshu and Bizen school swords.

3. Kakugata (角形) – “Squared Nakago”

  • The tang ends in a completely squared-off tip.
  • Seen in early chokutō (直刀) and later experimental blades.

4. Kengyō (剣形) – “Sword Tip Shape”

  • The tang ends in a sharply pointed shape, resembling a katana tip.
  • Often seen in Shintō and Shinshintō period swords.

5. Sotoba-Nakago-Jiri (卒塔婆茎尻)

  • Sotoba-nakago-jiri (卒塔婆茎尻) – Named after the Sotoba (卒塔婆), wooden Buddhist grave markers, this nakago-jiri has a stepped, tiered, or slightly slanted squared-off shape resembling these grave markers.

Types of Nakago shapes (Nakago no Katachi, 茎の形)

The shape of the nakago varies depending on the sword’s era, function, and forging tradition. Below are the primary nakago types:

1. Funagata (舟底)

  • Boat bottom shape

2. Tanago-bara (タナゴ腹)

  • “Sweetfish belly” shape, slightly bulging

3. Kijimono-nakago (雉子股茎)

  • “Pheasant thigh” shape, resembling a bird’s leg

3. Ha-agari Kuri-jiri (刃上がり栗尻) – “Raised Edge Chestnut Shape”

  • A chestnut-shaped nakago-jiri with the edge slightly raised.
  • Frequently found in Muromachi-period blades.

4. Shōgō-kengyō (正剛剣形)

  • Symmetrical kengyō shape

Types of Yasurimei (鑢目, File Markings on the Nakago)

Yasurimei (鑢目) are file marks applied to the nakago to provide grip and aesthetic appeal. Different schools and swordsmiths developed distinct yasurimei patterns, which serve as an identifying feature of their work.

1. Katte-agari (勝手上がり) – “Slanting Upward to the Right”

  • File marks angled diagonally from left to right.
  • Common in Shintō-period swords.

2. Katte-sagari (勝手下がり) – “Slanting Downward to the Right”

  • Opposite of katte-agari, with file marks slanting downward.
  • Used in some Kamakura-period blades.

3. Sujikai (筋違) – “Cross-Hatched Lines”

  • File marks form a steep diagonal pattern.
  • A signature of Soshu-den swords.

4. Kiri (切り) – “Horizontal Lines”

  • File marks are straight and horizontal, running perpendicular to the nakago.
  • Found in Edo-period katana.

5. Higaki (檜垣) – “Herringbone Pattern”

  • A crisscrossed, herringbone file pattern.
  • Common in Muromachi-period swords.

6. Ō-sujikai (大筋違) – “Wide Angle Cross-Hatching”

  • A larger, more spaced-out version of sujikai.
  • Found in long tachi and odachi.

7. Kesho-yasuri (化粧鑢) – “Decorative Yasurimei”

  • Highly stylized file markings used for aesthetic appeal.
  • Seen in presentation swords and high-quality custom pieces.