If you have a WW2-era Japanese sword with a signature on the nakago, you have something worth reading carefully. The mei on Shōwa-period blades follows a reasonably consistent format, and a collector with no prior knowledge of Japanese can understand its basic structure and determine whether a full translation is warranted.
This guide covers how mei are organised, how to convert the Japanese imperial calendar date into a Western year, what common Shōwa-period smith names look like, what the writing style tells you, and when the limits of self-assessment apply.
How a mei is structured
Japanese sword signatures follow a conventional layout that has remained largely consistent for centuries.
Omote (front face of the nakago): The smith’s name. This is the primary signature, the side you read first. It gives the smith’s name, often preceded by a province or school designation, and sometimes followed by an honorific or a craft title (e.g., saku, meaning “made”).
Ura (reverse face of the nakago): The date of manufacture, and sometimes additional information such as a location, a dedication, or a commission note. In Shōwa-period gendaitō, the ura inscription is typically a date in the imperial calendar, sometimes with a seasonal designation (spring or autumn).
Some Mantetsu and certain other wartime blades reverse this convention or combine information on a single face, but for most guntō the omote/ura split holds.
Reading the date: the imperial calendar
Shōwa-period blades are dated using the Japanese imperial era system, which counts years from the accession of the reigning emperor. The Shōwa era (Shōwa, 昭和, “Radiant Japan”) began in 1926 with the accession of Emperor Hirohito. To convert a Shōwa date to a Western year:
Shōwa year + 1925 = Western year
So Shōwa 18 (昭和十八年) = 1943. Shōwa 15 = 1940. Shōwa 20 = 1945.
The year is written using kanji numerals:
- 一 = 1, 二 = 2, 三 = 3, 四 = 4, 五 = 5
- 六 = 6, 七 = 7, 八 = 8, 九 = 9, 十 = 10
- 十八 = 18 (ten-eight), 二十 = 20 (two-ten)
The character 年 (nen) means “year” and follows the number. So 昭和十八年 = “Shōwa, eighteenth year.”
Seasonal designations are common on guntō and particularly on Mantetsu blades. 春 (haru) = spring; 秋 (aki) = autumn. These appear after the year character. A blade dated 昭和十八年春 was forged in spring of 1943.
Common Shōwa-period smith names
The wartime period saw a large number of smiths working under government and military contracts. Some names appear frequently in guntō collections:
- Yasukuni smiths: the Yasukuni shrine in Tokyo maintained a forge (Nihon Tanren Dojo) producing traditionally made gendaitō throughout the wartime period. Blades from this forge are among the most sought-after gendaitō. Smiths include Gassan Sadakatsu and various swordsmiths working under the Yasukuni designation.
- Seki smiths: Seki in Gifu Prefecture (formerly Mino Province, home of the Mino tradition) remained an active production centre. Many wartime blades signed with names containing Kane- (e.g. Kaneyoshi, Kanemoto) originate from Seki-area smiths following the Mino tradition.
- Gassan Sadaichi / Sadakatsu: significant gendaitō smiths of the Gassan lineage, working in the Gassan ayasugi tradition. Their blades command serious collector attention.
- Yoshichika, Masayuki, Nobuhide: names that appear across multiple wartime smiths; without a province or school prefix, these require additional context for attribution.
The first character or characters of the name often indicate province or school affiliation. Bishu (備州) indicates Bizen Province; Shu (州) means province generally; Rai (来) indicates Yamashiro-related lineage; Gassan (月山) is always the Gassan school.
What the writing style tells you
The quality of the chisel work on a mei is evidence: not conclusive in isolation, but meaningful.
Depth and confidence: A genuine nihonto mei cut by a skilled smith has depth and a sense of unhurried intention. The strokes are clear, the character forms correct, and the chisel angle consistent. Even a simple mei on a modest blade will have this quality if it is genuine.
Stamp versus chisel: Some wartime blades have stamped rather than chiselled signatures, particularly arsenal-inspected shōwatō. A stamped mei is shallower and more uniform than a hand-cut one. For traditionally made gendaitō, the mei should be chiselled.
Character accuracy: Japanese sword mei follow conventional character forms. If characters look distorted, abbreviated in unusual ways, or inconsistent with period convention, this may indicate a later addition or false inscription. This is harder to assess without reference, which is where translation consultation becomes useful.
A worked example
Consider the following hypothetical mei, structurally representative of a Spring 1943 Shōwa-period gendaitō:
Omote (front): 大和守兼道作
Ura (reverse): 昭和十八年春
Reading the omote:
- 大和守 (Yamato-no-kami): “Guardian of Yamato Province,” a traditional honorific title awarded to certain smiths
- 兼道 (Kanemichi): the smith’s given name; the character Kane (兼) is extremely common in Mino-tradition smith names
- 作 (saku): “made by”; a conventional closing character
Reading the ura:
- 昭和 (Shōwa): the era name
- 十八年 (jūhachi-nen): eighteenth year
- 春 (haru): spring
Full translation: “Made by Yamato-no-kami Kanemichi / Spring, Shōwa 18 [1943]”
This format (honorific title + name + saku on the omote, era + year + season on the ura) is typical of better-quality gendaitō from the wartime period.
Note that Yamato-no-kami as an honorific does not mean the blade is from the Yamato tradition; such titles were awarded to smiths from many provinces and persisted as conventions into the modern period.
The limits of self-assessment
This guide equips you to understand the structure and date of a mei, and to identify obvious features of the writing. It does not replace specialist translation for attribution decisions.
You should seek specialist input when:
- The characters are worn, partially visible, or in an archaic form you cannot identify
- You are considering a significant purchase and the mei is central to the attribution
- The name on the omote does not appear in any reference you can access
- The blade is being submitted for NBTHK shinsa
A clear photograph of the nakago, taken in good light, both sides, with no shadow obscuring the characters, is all a translator needs. We offer mei translation with a fast turnaround; the To-Ken Society of Great Britain and various online communities (the Nihonto Message Board in particular) can also assist.
For Mantetsu blades specifically, the serial and production designations on the nakago follow a documented format. See our post on identifying genuine Mantetsu blades for the detail.
Related guides: WW2 Japanese sword buyer’s guide · Periodisation of the Japanese sword
