NBTHK papers

NBTHK and NTHK: two acronyms that are not worth the same

The NBTHK — Nihon Bijutsu Tōken Hozon Kyōkai (日本美術刀剣保存協会), the society for the preservation of the Japanese sword as art — was founded in 1948, publishes the journal Tōken Bijutsu and runs the Japanese Sword Museum at Yokoami, in the Sumida ward of Tokyo. Its examinations, the shinsa, and its published criteria are the reference of the international market.

The NTHK — Nihon Tōken Hozon Kai (日本刀剣保存会) — is older: it goes back to 1910. Today two bodies use that name after a split, one of them written NTHK-NPO. Their certificates (kanteishō) come with a numerical score sheet:

NTHK grade	Points	Reading
shinteishō	60-69	genuine work
kanteishō	70-84	important work
yūshū-saku	85-94	very fine work
sai-yūshū-saku	95-100	work of the highest importance

Both systems are serious, but they are neither equivalent nor interchangeable: an NTHK paper is not a Hozon, and does not become one.

The four NBTHK levels

Level	Kanji	Sessions per year	What it certifies
Hozon	保存刀剣	four	a blade worth preserving: a correct signature, or a defensible attribution if unsigned
Tokubetsu Hozon	特別保存刀剣	four	especially worth preserving: better workmanship and better condition
Jūyō	重要刀剣	one	important, on a par with a state-recognised Important Art Object
Tokubetsu Jūyō	特別重要刀剣	one every two years	especially important, close to an Important Cultural Property

The order is compulsory and cumulative: only an item that already holds Hozon may be submitted for Tokubetsu Hozon; only one that passed Tokubetsu Hozon may go to Jūyō and only one that passed Jūyō may go to Tokubetsu Jūyō. No step is skipped, and the calendar sets its own pace: a blade cannot go from nothing to Jūyō in a single year. In practice, though, the NBTHK allows Hozon and Tokubetsu Hozon to be requested together at the first submission.

What each level demands, per the official text

The criteria are published; the version in force is the revision of 19 May 2015. In summary:

• Hozon: work no later than the Edo period with a correct signature, or unsigned (mumei) but with an identifiable period, province and lineage. Some tiredness or the odd flaw is tolerated if the blade is still worth appreciating, and repairs must not spoil the whole. From Meiji onward, only if signed and well made. Retempered blades (saiha) are rejected, except signed works by famous smiths no later than Nanbokuchō, of high documentary value and with little damage to blade and tang, which may pass with that noted. Doubtful cases are held over (horyū).
• Tokubetsu Hozon: among the Hozon blades, those of better workmanship and better preservation. Retempered blades are excluded, as are mumei works of the Muromachi and Edo periods, unless judged a superior work by a famous smith and in outstanding condition.
• Jūyō: among the Tokubetsu Hozon blades, those of particularly outstanding workmanship and good condition, comparable to an Important Art Object (jūyō bijutsuhin). Unsigned blades are admitted only if no later than Nanbokuchō; from Muromachi onward a signature is required, and from Edo onward, as a rule, an intact (ubu) signed tang.
• Tokubetsu Jūyō: among the Jūyō blades, those of outstanding workmanship, excellent condition and extremely high documentary value, equivalent to an Important Art Object or close to an Important Cultural Property (jūyō bunkazai).

Three rules common to every level: a large flaw that spoils the piece blocks a pass; works by living artists are not examined; and if a piece that already holds a certificate is submitted and fails, the result is «as is» (genjō) and it keeps the certificate it had.

Anatomy of a modern paper, field by field

The document follows a fixed format, meant to be read in columns, top to bottom and right to left. It is the same format for Hozon, Tokubetsu Hozon, Jūyō and Tokubetsu Jūyō: only the level printed changes and, from Jūyō onward, a photograph of the tang is added. The diagram beside this text marks where each piece of information sits.

1. Level granted: the exact name heads the paper: 保存刀剣, 特別保存刀剣, 重要刀剣 or 特別重要刀剣.
2. Type of item: what it is —刀 (katana), 太刀 (tachi), 脇差 (wakizashi), 短刀 (tantō)…
3. Signature: whether it is signed (銘) or unsigned (無銘); if signed, the inscription is transcribed exactly as carved.
4. Length: the nagasa (長さ), in centimetres, measured as explained in Anatomy of the katana.
5. Date of the examination: Japanese era, year, month and day of the shinsa session that decided it.
6. Registration number: a running number, specific to each level and each session.
7. Seals: the association's seal is embossed, not printed — you can feel it by running a finger over it, and it is the check most often cited against copies; next to it sits the seal or signature of the presidency.
8. Photograph or rubbing of the tang: from Jūyō onward, the paper carries a photograph (or an oshigata, an ink rubbing) of the nakago, with its signature and its mekugi-ana, so it can be checked against the blade in front of you.

The paper itself matters too: it is good-quality washi, with a feel unlike a photocopy or an office printout, and that is part of what an expert checks before the text.

The old papers, and why they do not count today

The NBTHK did not invent the practice of putting a judgement on a blade in writing. From the Edo period on, the Hon'ami family — polishers and appraisers in the shogunate's service — issued their own origami: a folded paper with the attribution and, often, a valuation in money. The one in the photograph, dated Genroku 15 (1702) and signed by Hon'ami Kōchū, certifies a tantō attributed to Yukimitsu and records its price: seventy pieces of gold (代金子七拾枚). NBTHK papers, unlike these, say nothing about money; they judge the piece alone. The word origami — “folded paper” — comes from there, and is still used today for any sword judgement, NBTHK or otherwise.

The diagram beside this text numbers the level, the date of the examination (in the Shōwa era), the registration number and the seal of whoever examined the piece; the three paper colours are detailed in the table:

1. Level: the ninteishō's name heads the paper; here, 特別貴重刀剣 (Tokubetsu Kichō).
2. Date of the examination: Shōwa era, between 1948 and 1982.
3. Registration number: specific to the session.
4. Seal of whoever examined it: a local branch or the head office.
5. Kichō ninteishō (貴重刀剣): white paper.
6. Tokubetsu Kichō ninteishō (特別貴重刀剣): green paper.
7. Kōshu Tokubetsu Kichō ninteishō (甲種特別貴重刀剣): blue paper.

Paper	Colour	Issued
Kichō ninteishō (貴重刀剣)	white	12 September 1948 to May 1982
Tokubetsu Kichō ninteishō (特別貴重刀剣)	green	March 1950 to May 1982
Kōshu Tokubetsu Kichō ninteishō (甲種特別貴重刀剣)	blue	September 1973 to May 1982
Jūyō tōken (重要刀剣)	—	from May 1958, head office only
Tokubetsu Jūyō tōken (特別重要刀剣)	—	from December 1971, head office only

In 1980 it came out that local branches had been passing items far above their merit, with organised crime involved. The branches stopped examining, and in September 1982 the NBTHK replaced every pre-Jūyō level with today's Hozon and Tokubetsu Hozon. Those ninteishō were neither converted nor revalidated: today they read as historical documents, not as attributions, and to hold a current opinion the blade has to go back to shinsa. Jūyō and Tokubetsu Jūyō, which were only ever issued by the head office, were untouched and are still trusted whatever their year.

Among collectors the argument is still alive: hundreds of thousands of papers were issued and many attributions were reasonable. But as a buying criterion a green paper supports nothing on its own, and resubmitting a middling blade usually confirms what was already known, or lowers it.

Papers for koshirae and for tōsōgu

The same four levels exist for the complete mounting (tōsō, 刀装) and for loose fittings (tōsōgu, 刀装具), judged separately from the blade. A well documented piece can arrive with three papers: one for the blade, one for the koshirae and one for the tsuba.

The emphasis shifts. For fittings: works up to the Edo period with a correct signature, or unsigned but with identifiable period and school; from Meiji onward, good workmanship and good condition; cast pieces later than Meiji are rejected; and at Tokubetsu Hozon level, visible repairs or alterations, over-polishing that erases the colour of age, and illegible signatures all count against. For mountings: no tsuba, no pass, aikuchi aside; a missing kozuka or kōgai is accepted and noted; a rewrapped hilt does not disqualify if it harmonises with the rest; and foreign-made mountings are not examined.

How to read a paper

The certificate (kanteishō; by custom it is also called an origami, though strictly that name belongs to the old appraisals) reads right to left and gives, in columns: the type of item and the length of the blade, the signature or the attribution, the level awarded, the date of the examination and the society's seal. A photograph of the tang (nakago) is attached, and there lies the check that really matters: that this tang, its holes and that signature belong to the blade in front of you, and that the length matches the real measurement.

Two warnings. The paper is for the blade, not for the ensemble: a Tokubetsu Hozon says nothing whatsoever about the mounting that comes with it, nor about the quality of the present polish. And the attribution can change as the levels rise: an unsigned blade assigned to a school at Hozon may receive a different attribution at Tokubetsu Hozon.

How to verify a paper

A paper is checked in two different directions: that the paper itself is genuine, and that the paper belongs to that blade. Confusing the two questions is the costliest mistake.

That the paper is genuine. The association's seal is embossed, not printed: you can feel it by running a finger over it, and it is the first thing anyone who has seen hundreds of papers checks. The NBTHK keeps a register of what it issues and answers enquiries about it; for an important piece, writing to ask or, better, bringing the blade and the paper together to the Tokyo office is the definitive check. Forgeries have turned up even of Hozon and Tokubetsu Hozon, the most common levels, so caution is not only a matter for old papers.

That the paper belongs to that blade. This is where the photograph or oshigata of the tang that papers carry from Jūyō onward earns its keep: check, one by one, that the number of mekugi-ana matches, that they sit in the same position, that the yasurime is the same, and that the signature — if there is one — reads the same in the photo and on the real blade. The length written on the paper has to match the nagasa measured on the piece; if it does not, either the paper is not for that blade, or the blade has changed since the examination. By convention, too, a tachi's signature and a katana's sit on opposite faces of the tang, so the face the mei appears on in the photo is also worth checking.

A paper without the blade beside it, or sold apart from it, is a reason to ask more questions, not fewer: the international market has seen genuine papers paired with a different blade from the one they certified.

What each level means for value

A paper does not set a price: it certifies a panel's judgement on a given date, and it is the market that decides how much to pay for it. Even so, the level shapes value fairly consistently, because it shapes rarity.

The calendar already hints at it: Hozon and Tokubetsu Hozon are examined four times a year; Jūyō, once; Tokubetsu Jūyō, once every two years, and only among what already holds Jūyō. Each step filters the one before it, so the population narrows fast. According to figures published for the fiftieth anniversary of the Tokubetsu Jūyō system, in 2021 there were 1,143 blades holding that designation, against the tens of thousands that hold Hozon or Tokubetsu Hozon: the gap in rarity between one level and the next is not gradual, it is a different order of magnitude, and the market reflects that in price more than in any other item on a listing.

The diagram beside this text numbers the shinsa cadence of each level and the extremes of rarity:

1. Hozon: four shinsa sessions a year.
2. Tokubetsu Hozon: four sessions a year, only for what already holds Hozon.
3. Jūyō: one session a year, only for what already holds Tokubetsu Hozon.
4. Tokubetsu Jūyō: one session every two years, only for what already holds Jūyō.
5. Base of the pyramid: the most common level.
6. Tip of the pyramid: the rarest level.

That said, each level plays a different role:

• Hozon is the threshold separating a seriously collectable blade from an unstudied one: it certifies that the signature or the attribution holds up, not that the piece is exceptional. It is, by far, the most common paper, and the first thing any serious buyer asks for.
• Tokubetsu Hozon picks out, among what is already approved, the better workmanship and the better condition; in practice it is the level most actively traded among collectors, because it combines relative availability with quality already filtered.
• Jūyō is the real jump: a single session a year, only for what already passed Tokubetsu Hozon, and a standard compared to a state-recognised Important Art Object. The international market treats the line between Tokubetsu Hozon and Jūyō as the one separating a good blade from an important one.
• Tokubetsu Jūyō is the exception within the exception: one thousand one hundred and forty-three blades in the entire history of the level, as of 2021. A paper at this rank approaches, in treatment and in price, an Important Cultural Property.

Two warnings against reading the level as if it were the price. First, the paper judges the blade, not the whole: a Tokubetsu Hozon with a tired polish or a poor mounting is worth less than an equally graded one that is well kept, and the paper says nothing about that. Second, the level is not final: a blade can be resubmitted years later and rise, if research on its school or its smith has moved on, or stay where it was if it fails — recall the genjō rule. And between NBTHK and NTHK, though both are serious bodies, the international market calibrates its prices on NBTHK figures; an NTHK paper does not simply translate into an equivalent NBTHK level.

The tōrokushō is not a certificate of authenticity

The tōrokushō (銃砲刀剣類登録証) is the registration required by the Japanese firearms and swords law of 1958. It is issued by the prefectural board of education at monthly registration sessions, stays with the blade for as long as it remains in Japan, and obliges the owner to report a change of ownership within twenty days. The blade is registered, not its owner.

What it records is the length, the curvature, the number of mekugi-ana and what the signature says. It does not judge whether that signature is genuine, nor the quality, nor the date. Mistaking it for a paper of authenticity is the commonest error of first-time buyers, and Japanese listings often mention it as «Japanese registration included».

On export the tōrokushō is handed back and the Agency for Cultural Affairs (文化庁) issues in its place an export inspection certificate for antiquities (古美術品輸出鑑査証明). Items designated Important Cultural Property or National Treasure may not leave Japan. That is why a blade that reaches Europe legally comes without its tōrokushō: its absence says nothing, good or bad, about the piece.