A Rare Long Sword by Samonji
The Tachi Sword (signed Chikushu ju Sa; known as Kosetsu Samonji) (太刀〈銘筑州住左（江雪左文字）〉) is a Nanbokucho-period tachi by Samonji at the Fukuyama Museum of Art in Nishimachi, Fukuyama City, Hiroshima Prefecture, which in 1951 was designated a National Treasure.
The Agency for Cultural Affairs records one blade 78.2 centimetres long with a curvature of 2.7 centimetres and 3.3 centimetres wide at the base, owned by Fukuyama City, first designated under the old system in 1933.
According to the Agency, it takes the name Kosetsu Samonji from Okabe Kosetsusai Tsugunari, a retainer of the Hojo clan, who treasured it.
The Blade
According to the Agency, it is ridged with a roof-shaped back, broad, with a somewhat extended point. The steel is a fine grain with thick crystals, dark lines and scattered spots of temper. The temper line is bright and deeply crystalline, a large irregular pattern with legs and sweeping lines.
The point pattern runs irregularly upward and turns back fairly deep. Grooves were carved on both faces later, and the shortened tang keeps diagonal file marks low on the front, with a finely cut signature.
What to Look For
The Agency explains that Sa, son of Jitsua of Chikuzen, is said to have studied under Masamune of Soshu, and is called Samonji from signing his blades with the character sa. This is a masterpiece of the first Samonji; as he excelled at daggers, signed long swords are rare, but this one is no less fine.
The Agency adds that it later belonged to Tokugawa Ieyasu and was given to Yorinobu of Kii.
Visiting the Tachi Sword (signed Chikushu ju Sa; known as Kosetsu Samonji)
The sword is at the Fukuyama Museum of Art and is not always on display; check the museum's schedule.
Q&A
- When was it designated a National Treasure?
- On 9 June 1951.
- Where does the name come from?
- From its owner Okabe Kosetsusai, a Hojo retainer.
- Who was Samonji?
- A smith of Chikuzen said to have studied under Masamune.
- What is its history?
- It passed to Tokugawa Ieyasu and then to Yorinobu of Kii.
- How big is it?
- 78.2 cm long with a curvature of 2.7 cm.
Basic Information
| Name | Tachi Sword (signed Chikushu ju Sa; known as Kosetsu Samonji) (太刀〈銘筑州住左（江雪左文字）〉) |
|---|---|
| Location | Fukuyama Museum of Art, 2-4-3 Nishimachi, Fukuyama City, Hiroshima Prefecture |
| Designation | National Treasure (craft) |
| Year Designated | Designated 1951/6/9 (Showa 26); earlier designation 1933/1/23 |
| Quantity | 1 blade |
| Dimensions | 78.2 cm long, curvature 2.7 cm, 3.3 cm wide at the base |
| Owner | Fukuyama City |
| Public Access | Check display with the museum |
References
- Agency for Cultural Affairs Database: Kosetsu Samonji (Japanese)
- https://kunishitei.bunka.go.jp/bsys/maindetails/201/305
- Fukuyama Museum of Art official website (Japanese)
- https://www.city.fukuyama.hiroshima.jp/site/fukuyama-museum/
Last verified: 2026.10.01