If you have inherited, purchased, or are considering buying a WW2-era Japanese sword, the first question, before anything else, is this: is it a nihonto or a shōwatō? The answer determines everything about the blade’s scholarly and collector value, and it is a question you can begin to answer yourself, with the right guidance.
What these terms mean
Nihonto (日本刀) means, literally, “Japanese sword,” but in collector usage the term has a precise technical meaning. A nihonto is a sword forged by traditional methods: the smith begins with tamahagane (steel produced in the tatara smelter from iron sand and charcoal), works the material through repeated folding and consolidation to produce a differentiated blade, and achieves the hardened hamon through differential clay application and water quenching. The entire process is done by hand. Nihonto of all periods, from Heian tachi through Meiji and Taishō gendaitō, share this fundamental method.
Shōwatō (昭和刀) means, literally, “Shōwa-period sword,” but in practice the term refers specifically to machine-made military blades produced for officer issue during the 1930s and 1940s. These blades were manufactured from industrially produced steel by methods that bypassed the traditional forging process entirely: stamped or drop-forged, with an acid-etched simulated hamon rather than a genuine differentially hardened one. They were produced in very large numbers to supply the rapidly expanding officer corps, and they are by far the most common WW2-era Japanese sword found in Western collections today.
The distinction matters because nihonto, even later gendaitō of modest quality, have genuine collector and scholarly value. Shōwatō, being industrially produced, are primarily historical artefacts of the conflict rather than examples of the swordsmith’s art.
The visual differences
You will need to draw the blade carefully and examine it under good natural or diffuse artificial light. Never touch the polished surface with bare hands.
Hada (surface grain)
This is the most reliable single indicator.
A nihonto, being folded steel, has a visible surface texture known as hada or jihada, the crystalline grain pattern produced by the folding and forging process. Under light, the ji (the area between the shinogi ridge and the hamon) will show a pattern: itame (overlapping, wood-grain-like), mokume (rounded, burl-like), masame (straight, parallel), or some combination. In a well-polished blade this texture is clearly visible. Even in an older polish, the structure is present, if harder to read.
A shōwatō has no such grain. The ji is smooth and undifferentiated, more like modern tool steel, because that is what it is. There may be surface marks from the manufacturing process, but the characteristic crystalline vitality of folded steel is absent.
Hamon (temper line)
A nihonto’s hamon is the product of differential hardening: clay is applied to the blade before quenching, controlling where the steel transforms to martensite. The hamon has a living internal quality, whether nie (bright crystalline granules) or nioi (a misty, diffuse boundary), and shows the activities of the transition zone: ashi (short legs descending into the hamon), yō (floating activity within), kinsuji, sunagashi. The boundary between hamon and ji is a physical, three-dimensional transition in the steel.
A shōwatō’s hamon is etched onto the surface with acid. It looks painted on: a uniform line without internal activity, without nie or nioi, without depth. Under magnification the difference is stark. Under strong raking light, a genuine hamon catches the light in a way an etched line cannot replicate.
Nakago (tang)
The nakago, the portion of the blade that sits inside the handle, is often the clearest area for comparison.
On a nihonto, the nakago shows natural oxidation over time: a dark, even patina called kurokami (black skin), sometimes with an interesting surface texture. File marks (yasurime) on the nakago surface are hand-cut and visible as distinct, angled lines. The shape of the nakago, its profile and tip form and the position and size of the mekugi-ana (peg hole), follows conventions that kantei practitioners read as evidence of period and school.
On a shōwatō, the nakago is typically machine-finished, cleaner and more uniform, with file marks that may appear mechanical rather than hand-cut. The metal itself may look and feel different to the touch, less complex and less differentiated.
Arsenal stamps
Many shōwatō bear stamps on the blade or nakago that identify the arsenal or contractor that produced them. Common stamps include the Tokyo Artillery Arsenal (a cherry blossom or star variant), the Kokura Arsenal, and various naval and army production marks. The presence of an arsenal stamp is strong evidence, though not absolute proof, that a blade is machine-made. Genuine nihonto were occasionally submitted to arsenal inspection, but they were not typically stamped in the same way.
The resource that English-language collectors rely on for guntō stamp identification is ohmura-study.net, a detailed reference catalogue of WW2-era Japanese military sword production compiled from primary sources. If you have stamps on your blade that you cannot identify, that site is the first place to look.
Mei quality
The mei, the signature on the nakago, is worth examining, but it requires caution as a standalone test. Genuine nihonto often have a chiselled mei with depth and character; shōwatō may have a stamped or shallowly engraved inscription. However, some gendaitō smiths who used traditional methods still produced comparatively plain signatures, and some shōwatō have mei that superficially resemble nihonto work. Read the mei alongside the other evidence, not instead of it.
What to do once you know
If your blade is a shōwatō: it is a genuine WW2 artefact with historical interest. It may have value as militaria, particularly if it retains complete mounts, a tassel, a blood channel, or documented provenance. It is not a nihonto, and should not be priced as one. Treat it with appropriate care, since these blades were still functional weapons and remain sharp.
If your blade is a nihonto: the next step is understanding what kind, from what period, and with what attribution. Visible mei on the nakago can often be translated (we offer that service), and the combination of school features and inscription will point toward a more specific identification. For pieces of potential value, NBTHK shinsa (formal appraisal) via a UK or US submissions coordinator is the definitive route to authentication.
If you are genuinely uncertain after examining the blade yourself, the correct step is to consult a specialist. The cost of an assessment is modest relative to the cost of a mistaken sale or purchase.
The archive on this site includes examples of both nihonto and shōwatō in period mounts, with provenance notes. It makes a useful comparison set if you are building your eye.
Related guides: WW2 Japanese sword buyer’s guide · Periodisation of the Japanese sword
