The Sanchōmō (山鳥毛)

The measurements, source by source

The reference figures are those of the Agency for Cultural Affairs’ cultural-heritage database and those of the museum leaflet: 刃長 (hachō) 79.1 · 反り (sori) 3.3 · 元幅 (motohaba) 3.5 · 先幅 (sakihaba) 2.2 · 鋒長 (probable reading: kissaki-naga; length of the kissaki) 3.3 (cm). The others differ through rounding, copying errors or measuring in another way. In centimetres, except the weight.

The column from the 『日本刀大百科事典』 (Nihontō Dai Hyakka Jiten), by Fukunaga Suiken, we have only seen in secondary transcriptions; the work itself could not be consulted.

Figure by figure

1. Nagasa: 79.1 cm. The Uesugi house register of swords (1898) gives “長 弐尺六寸壱分” (nagasa ni shaku roku sun ichi bu), which is 79.1 cm: it matches the official figure. The 80.3 (2尺6寸5分, ni shaku roku sun go bu) is only partly explained by measuring from the ha-machi (that would give about 79.7). Measured along the curve of the back, the blade gives about 79.5, exactly the city’s 2019 figure; along the curve of the edge, about 80.3–80.4. It may also be a misprint in copying 2尺6寸1分 (ni shaku roku sun ichi bu). In any case, 80.3 is not an official figure.
2. Sori: 3.3 cm. The city council gave 3.4 cm in 2019 and Wikipedia gives 3.2. The difference from 3.18 falls within reading or rounding errors; without the printed source it cannot be resolved.
3. Motohaba 3.5, sakihaba 2.2 and kissaki 3.3 cm: the figures of 3.48, 2.18 and 3.33 are the same measurements unrounded. There is no real discrepancy.
4. Nakago: about 22–23 cm. There is no official figure, and the conversion in circulation is wrong: 7寸6分5厘 (nana sun roku bu go rin) is 23.18 cm, not 22.18.
5. Weight: 1.06 kg, published by the city council in 2019 and in 2020. It is not stated whether this is the bare blade or with the habaki. Our own calculation gives 1.01–1.07 kg for the bare blade with a bōhi running to the end of the nakago: it fits the blade alone, not the mounted blade.
6. Kasane: there is no official figure. Secondary sources give about 0.9 cm at the base (3分弱, san bu jaku) and about 0.5 cm at the point (1分6厘弱, ichi bu roku rin jaku).
7. The Okayama prefecture record is wrong: 71.2 cm and a sori of 2.7 cm match no other record.

The official text, in English

• Jihada: itame with a faint midare-utsuri. Secondary sources add mokume, fine ji-nie and a somewhat visible steel.
• Hamon: ō-chōji midare of jūka-chōji type, so high that it almost reaches the shinogi, with abundant and highly varied ashi and yō; at the base and below the monouchi, strong nie and kinsuji. The museum leaflet adds tobiyaki everywhere and a hamon mainly of nioi, with areas of nie.
• Bōshi: on the omote face, broad, it runs in in large waves and turns back with hakikake; on the ura, midare-komi. Wikipedia describes the ura as notare with a komaru turn-back.
• Horimono: bōhi on both faces, running to the end of the nakago. The leaflet explains it as a device “to lighten the blade and make it easier to wield”.
• Nakago: ubu, with katte-sagari yasurime, unsigned and with 2 mekugi-ana. Kurijiri, according to Wikipedia.
• A nick a little above the habaki. The leaflet interprets it as proof that the tachi was used in combat.

For the Agency it is a work “日光一文字と並ぶ” (Nikkō Ichimonji to narabu), on a par with the Nikkō Ichimonji, and “刃文が最も大模様に乱れて刃中の変化に富んだ作” (“a work whose hamon has the largest irregular pattern and the greatest variety of activity in the edge”). According to Wikipedia, Satō Hirosuke (Tokyo National Museum) believes the hamon is the product of chance and unrepeatable, and Watanabe Taeko (Sano Museum) considers it impossible to reproduce. No swordsmith can promise an exact copy of this hamon.

The name “山鳥毛” (Sanchōmō)

• The official version: “号は、一説にその刃文が山鳥の羽毛に似ているからというが、他にも説があって明らかでない” (“the name comes, according to one account, from its hamon resembling the plumage of the copper pheasant, but there are other accounts and it is not clear”). The name would come, according to one account, from the hamon resembling the plumage of the 山鳥 (yamadori), but there are others and it is not clear. The 山鳥 (yamadori) is the Japanese copper pheasant.
• The city council records both images: the pheasant’s plumage and “山野が燃えるよう” (san'ya ga moeru yō), a mountain in flames.
• The note in the 1898 Uesugi register: “又山焼毛トモ謂フ、蓋シ焼刃ノ美ナル山鳥ノ尾毛、山野ノ燃ユルノ状ニ似タルヲ以テ” (“it is also called ‘hair of the burning mountain’, for the beauty of its hardened edge recalls the tail feathers of the copper pheasant and a mountain on fire”).
• The reading さんちょうもう (Sanchōmō) comes from Uesugi Kagekatsu’s autograph inventory, which writes it “山てうもう” (Sanchōmō, in the old spelling).

From Uesugi Kenshin to Setouchi

The purchase by Setouchi

• The city bought the Sanchōmō without taxpayers’ money, with donations from citizens and companies: donations to municipalities (ふるさと納税, furusato nōzei) and a crowdfunding campaign.
• According to the final official account, 17,354 individuals and 154 organisations donated, and the sum raised, after expenses, covered 125.5 % of the target.
• An external committee valued the sword, counting its economic effect on the city, above what was paid.
• Helping factors were the “a day in your charge” form of donation (一口佩刀, probable reading: hitokuchi haitō; from October 2019), the display of the sword at the museum in October 2019, with some 5,500 visitors, and the arrival of the “Sanchōmō” character in the video game Tōken Ranbu in December 2019.
• In 2021 the initiative received a commendation from the Minister for Regional Revitalisation.

Where to see it HD

The Sanchōmō is not on permanent display: the Bizen Osafune Japanese Sword Museum shows it roughly once a year. On 26 September 2026 the 2026 season had already ended and the 2027 one had no dates.

The museum offers a virtual-reality viewing of about six minutes and a 4K touch screen for seeing the blade from angles impossible in the showcase.

Known utsushi

• Ōno Yoshimitsu (大野義光) made several utsushi (1984, 1986 and 2004), which are reckoned among the best of his work; they were exhibited in 2019–2021.
• The official utsushi is by Andō Hiroyasu (安藤広康), a swordsmith from Okayama, who finished it in November 2022 for the city of Setouchi, as a gift to the donors, after more than a dozen attempts, of which only two were carried through to the end. Andō: “刃文は偶然の産物。コントロールして出すのは難しい” (“the hamon is the product of chance; it is hard to bring it out at will”).
• The Sankei says that the city council asked “安藤さんら刀工” (Andō-san ra tōkō), Andō and other swordsmiths, for utsushi. Kawashima may have been one of them; it is not confirmed.
• An unnamed swordsmith examined the Sanchōmō on 30 August 2018 to make an utsushi.

Kawashima and the Sanchōmō: what can be stated II

Each statement, with its level and its basis. The conclusion: Kawashima is pursuing the Sanchōmō, but has not finished any utsushi of the Sanchōmō on record.