Kantei
A long, curved tachi blade, whole, on a black background, with the tang on the left and the point on the right.

Bizen · Osafune · Kamakura

Osafune Nagamitsu (長光)

The swordsmith of Osafune, in Bizen, of the second half of the Kamakura period: his life and his school, his style, his National Treasures and his sources

Nagamitsu (長光, Nagamitsu) forged in Osafune, in Bizen Province, in the second half of the Kamakura period. The son of Mitsutada according to tradition, he has dated work from 1274, and more of his blades designated National Treasure or Important Cultural Property survive than of any other swordsmith, according to the Japanese Wikipedia.

Tokyo National Museum, via ColBase

1274
His earliest dated blade
1304
His last dated work
6
National Treasures
28 or 33
Important Cultural Properties, depending on the source
On this page
  1. Quick profile
  2. In short

Quick profile

Name
Nagamitsu, of Osafune; in his late work he also signs as 左近将監 (Sakon-no-shōgen) HD
Kanji and reading
長光 (Nagamitsu) · 長船長光 (Osafune Nagamitsu) HD
Period
Second half of the Kamakura period: dated work from 1274 (文永十一年, Bun'ei jūichinen). Kotobank places his work between the Bun'ei and Kagen eras (1264–1306), with dated work up to 1304 (嘉元二年, Kagen ninen); the years of his birth and death are not known. HD
Province
Bizen (備前, Bizen): Osafune, today in Setouchi, Okayama Prefecture HD
School
Osafune (長船派, Osafune-ha), in the Bizen tradition HD
Master
His father, 光忠 (Mitsutada), according to tradition AT
Generations
Old tradition distinguished two Nagamitsu; today the prevailing view is a single swordsmith with some thirty years of work AT
Documented fact and tradition
Documented: his dated blades of 1274 and 1285, and his designated works. From tradition: that he was the son of Mitsutada, the two generations and that 順慶 (Junkei) was his monk’s name. HD

In short

What we know. The NBTHK takes as certain his works dated 1274 (Bun'ei 11) and 1285 (Kōan 8). The one of 1274 is the earliest dated blade of the whole Osafune school. Six of his works are National Treasures, among them the tachi Daihannya Nagamitsu in the Tokyo National Museum.

How we know it. From his signed and dated blades, from the records of the Agency for Cultural Affairs and from the studies of the NBTHK. The list of his designated works comes from the Japanese Wikipedia and Kotobank.

What we do not know. When he was born and when he died; whether there were one, two or three swordsmiths with his name; and how many of his works are Important Cultural Properties: the sources give 28 or 33, and they remain to be counted in the Agency’s register.

Sections

  1. Mitsutada · Osafune · 1274–1304 Life and times His school, his thirty years of dated work, the question of the two generations and his pupils.
  2. Chōji · suguha · midare-utsuri Work and style Kantei keys to his work: the shape, the steel, the temper, the point and the signature.
  3. Daihannya · Tōtōmi · Kumano Famous works His National Treasures, his Important Cultural Properties and his place in the old lists.
  4. Museums and the city of Setouchi Videos His tachi in two museums and the reproduction of the Daihannya Nagamitsu presented by the city of Setouchi.
  5. Bibliography and credits Sources The sources consulted on 4 October 2026, with their link, and the credit for each image.