A Tachi Signed "Shinbo saku"
Near the back edge of this sword's tang, above one of two peg-holes, a smith cut three small characters: Shinbo saku, "made by Shinbo." Those three characters carry a great deal of weight, because they are almost all we can say for certain about who made the blade and when.
The sword is a tachi, the long, deeply curved type that a mounted warrior wore slung edge-down from the waist. It runs 75.0 centimeters along the cutting edge, with a pronounced curve of 2.3 centimeters that sits low toward the hilt. That low, generous curve is one of the oldest features a Japanese sword can show. It belongs to a time when blades were drawn on horseback rather than from a standing draw, and it points back to the late Heian and early Kamakura periods, roughly the twelfth and early thirteenth centuries.
The construction is shinogi-zukuri, the ridged cross-section that became the classic shape for a curved Japanese blade, finished with an iori-mune back ridged like the gable of a roof. The surface steel is forged in a wood-grain pattern called itame. Along the edge runs a temper line of choji, irregular clusters shaped like cloves, and the hardened pattern in the point, the boshi, turns back in a rounded sweep. These are the marks a connoisseur reads the way a reader follows handwriting.
Who Was Shinbo?
The name Shinbo, written 信房 and read Nobufusa, sits at a genuine fork in sword history. Two early traditions claim it. One is the Ko-Bizen ("old Bizen") school of Bizen province, today the southeastern part of Okayama Prefecture, whose smiths worked in the quiet decades of the late Heian period. The other is the Ichimonji line, an early Bizen group whose first masters served the retired emperor Go-Toba as his rotating court smiths in the early thirteenth century.
Collectors long drew a rule of thumb between the two. A blade signed with only the two characters of the name, 信房, was read as Ko-Bizen and dated earlier; a blade signed with the three characters 信房作, adding "made," was read as the Ichimonji Shinbo and dated to the early Kamakura years. Some scholars argue the two were never separate men at all. This blade carries the three-character form.
The dating follows the attribution. The national register lists the period as Heian, the reading that fits a Ko-Bizen smith. The traditional view, supported here by the blade's own fittings, places it a little later, in the early Kamakura work of the Ichimonji school. The article keeps both readings in view rather than forcing a single answer, because the surviving evidence does not settle it.
From Old National Treasure to Important Cultural Property
This sword was first listed as a National Treasure in 1916, under the prewar system of cultural property law. When Japan rewrote that system with the Cultural Properties Protection Law of 1950, the older National Treasures were reviewed and reissued under new categories. On 29 August 1950 the blade was registered as an Important Cultural Property, designation number 01399, a status it still holds. The earlier "National Treasure" label and the present "Important Cultural Property" label describe the same object under two different legal regimes, not a demotion in quality.
Two of the sword's companions are recorded with it. The first is an itomaki-no-tachi mounting, the formal court-style scabbard and hilt wrapped in cord. The second is the brocade that wrapped the blade: a light-green silk woven with roundels of dragons and auspicious treasures, and with the words "Ichimonji Shinbo" worked into the cloth itself. That woven attribution is the clearest sign that the sword's later owners regarded it as Ichimonji work. A striped paulownia box finished in shunkei lacquer completes the set.
The provenance reaches the highest level of Edo-period society. The blade was dedicated by Tokugawa Mitsutomo (1625 to 1700), the second lord of the Owari branch of the Tokugawa house, one of the three senior Tokugawa families. A sword given by an Owari lord was a gift of real political and ceremonial weight, the kind of object that anchored alliances and marked important occasions.
A Treasure Currently Out of Sight
There is one more thing a visitor needs to know before planning a trip. This particular sword cannot be seen. It appears on the Agency for Cultural Affairs' public register of designated cultural properties whose whereabouts are no longer known to the state. Its owner is recorded only as a private individual in Tokyo, and the Agency invites anyone with information about the blade to come forward.
That status is worth understanding rather than glossing over. A designated property in private hands can pass through inheritance, sale, or simple loss of contact with the authorities until its location drops off the official record. The designation itself stays in force, which is why the sword still carries its number and still appears in the database. For now, though, no museum holds it and no exhibition shows it.
The good news for a traveler is that the world this blade came from is very much on view. Several closely related swords, including one by a smith of the very same name, can be seen in public collections, and they let you read the same craftsmanship at close range.
Where to See Comparable Swords Today
The single best stand-in sits in Yamagata Prefecture. The Chido Museum in Tsuruoka holds the only blade by Shinbo ever raised to National Treasure rank, a tachi signed in the same three-character form, "Shinbo saku," and kept with its own court-style mounting. It came down through the Sakai family, lords of the Shonai domain, after Tokugawa Ieyasu presented it to Sakai Tadatsugu for his service at the battle of Komaki and Nagakute in 1584. The museum shows it only on special occasions, often about once a year, so check the current schedule before you travel. The Chido Museum stands on the old Sakai residence grounds beside Tsuruoka Castle park and is about ten minutes by bus from Tsuruoka Station; the same site preserves several Meiji-era buildings that are themselves Important Cultural Properties.
Closer to where this lost blade was last recorded, the Japanese Sword Museum in the Yokoami district of Sumida, Tokyo, run by the Society for Preservation of Japanese Art Swords, holds an Important Cultural Property tachi by Shinbo as well, alongside other National Treasures and designated blades. It is a short walk from Ryogoku Station and sits near the Edo-Tokyo Museum and the Kokugikan sumo arena, which makes for an easy half-day in the old eastern city.
To understand the Ichimonji style that this sword is traditionally tied to, the Tokyo National Museum in Ueno is the place to go. Its holdings include celebrated Fukuoka Ichimonji tachi by smiths such as Yoshifusa and Sukezane, whose bright, exuberant clove-pattern temper lines show the school at full stride. Seeing one of those beside the rounded, lower-key temper of a Shinbo blade makes the family resemblance, and the differences, easy to grasp.
- 📍 Plan Your Visit to Tokyo
- Find tours, activities & transport passes near Tachi Sword (inscribed with Nobufusa's Name)
- [ Tokyo Skytree Asakusa & teamLab Experiences ]
Q&A
- Can I see this particular sword anywhere?
- No. The blade is on the Agency for Cultural Affairs' register of designated properties whose location is currently unknown, and it is owned privately rather than held by a museum. There is no exhibition or public display of it at this time.
- Was Shinbo a Ko-Bizen smith or an Ichimonji smith?
- Both names exist in early sword history, and scholars still debate the question of one smith versus two. The three-character signature on this blade, together with a brocade that names "Ichimonji Shinbo," points to the Ichimonji line, while the national register dates the work to the Heian period, which would suit a Ko-Bizen reading.
- Why is it called an Important Cultural Property if it was once a National Treasure?
- It was designated a National Treasure in 1916 under the older law. When the Cultural Properties Protection Law took effect in 1950, prewar National Treasures were reissued, and this blade became an Important Cultural Property on 29 August that year. The change reflects a change in the law, not a lower assessment of the sword.
- What does "Shinbo saku" mean and where is it on the sword?
- It means "made by Shinbo." The three characters are cut into the tang, the unpolished section of metal that fits inside the hilt, near the back edge above a peg-hole. The tang is shaped in the so-called pheasant-thigh form used on courtly blades.
- Where can I see a comparable sword by Shinbo?
- The Chido Museum in Tsuruoka, Yamagata, owns the only National Treasure by Shinbo and shows it on occasion. The Japanese Sword Museum in Sumida, Tokyo, holds an Important Cultural Property tachi by Shinbo. The Tokyo National Museum displays related Fukuoka Ichimonji blades.
Basic Information
| Name | Tachi, signed "Shinbo saku" (Tachi, mei Nobufusa saku) |
|---|---|
| Category | Craft (sword); Important Cultural Property |
| Designation | National Treasure under the old law (1916); re-registered as Important Cultural Property on 29 August 1950; designation no. 01399 |
| Smith | Shinbo (Nobufusa); attributed by tradition to the Ichimonji line, dated by the national register to the Heian period |
| Count / Dimensions | 1 piece; cutting-edge length 75.0 cm, curvature 2.3 cm |
| Form | Shinogi-zukuri with iori-mune back; itame (wood-grain) forging; choji (clove) temper line; rounded boshi; two peg-holes |
| Accompanying items | Itomaki-no-tachi mounting; light-green dragon-and-treasure brocade woven with "Ichimonji Shinbo"; striped paulownia shunkei-lacquer box |
| Provenance | Dedicated by Tokugawa Mitsutomo (1625 to 1700), second lord of the Owari Tokugawa house |
| Owner / Location | Private individual, Tokyo |
| Public access | Not on display; whereabouts currently unknown per the Agency for Cultural Affairs register |
References
- National Database of Designated Cultural Properties (Agency for Cultural Affairs): Tachi, signed Shinbo saku
- https://kunishitei.bunka.go.jp/bsys/maindetails/201/6272
- Agency for Cultural Affairs, register of cultural properties whose whereabouts are unknown: Tachi, signed Shinbo saku
- https://www.bunka.go.jp/seisaku/bunkazai/torimodosou/kunishitei/50.html
- Cultural Heritage Online (National Institutes for Cultural Heritage): Tachi by Shinbo (Japanese Sword Museum)
- https://bunka.nii.ac.jp/heritages/detail/183672
- Cultural Heritage Online: Tachi signed Shinbo saku, with itomaki-no-tachi mounting (National Treasure, Chido Museum)
- https://online.bunka.go.jp/heritages/detail/101029
- Chido Museum, official site (access and visitor information)
- https://www.chido.jp/access/
Last verified: 2026.06.14