Advanced Guide to Reading the Nakago: Unlocking Sword History Through File Marks, Peg Holes, and Signatures

The Nakago as Historical Document

The nakago (tang) — the portion of the blade inserted into the handle, normally hidden — concentrates four types of historical evidence: the mei (signature), yasuri-me (file marks), mekugi-ana (peg holes), and rust color and texture. Reading them together allows authentication, provenance determination, and reconstruction of alteration history.

Yasuri-me: The Smith's Fingerprint

File marks are practical (providing grip for handle wrapping) but primarily function as school and period indicators. Major types include katte-sagari (right-downward lines, most common), suji-chigai (crossing diagonal lines, common in Bizen and Mino), and kiri (horizontal lines, Yamashiro and early period). File marks can be subsequently altered, so they should never be the sole basis for attribution — always cross-reference with hamon, jihada, and other evidence.

Mekugi-ana: The Record of Use

Single peg holes are standard in post-Muromachi swords. Multiple holes indicate: replacement handles made at different times; suriage (blade shortening) requiring new holes; or o-suriage conversion of a tachi to uchigatana form. Comparing the rust depth in multiple holes reveals which hole is older, providing a relative chronology of the blade's history.

Reading the Mei

Surface inscriptions typically record the smith's name, and may include province designation, court title, manufacturing year, or provenance notes. Suriage (shortening) can remove or relocate original signatures — "kaerimei" preserved signatures by relocating them to the tang's edge. The distinction between legitimate signatures, blank unsigned (mumei) nakago, and forged signatures is central to authentication.

Nakago Shape and Rust

Tang shape (tip form and profile) varies by period and school, providing additional attribution data. Rust color is particularly valuable: the "ai-iro" (sky-blue) deep dry rust characteristic of genuine ancient swords is difficult to fake convincingly, though artificial "sabi-ire" rust forgery techniques exist and require expert examination to detect.