Osafune Kiyomitsu

Osafune Kiyomitsu was a swordsmith who was active in Osafune in Bizen Province (present-day Setouchi City, Okayama Prefecture) from the mid to late Muromachi period. He is one of the master smiths representing the Sue-Bizen period, when the Bizen Osafune school's mass-production system became fully established. To distinguish him from Kashū Kiyomitsu, he is also called Bizen Kiyomitsu. In Osafune, several smiths who took the name "Kiyomitsu," such as Gorozaemon-no-jō Kiyomitsu and Magoemon-no-jō Kiyomitsu, were active across several generations.

Osafune in the mid-Muromachi period, when Kiyomitsu was active, was a time when demand for swords rose sharply as warfare deepened after the Ōnin War (1467–1477). Production shifted from the Osafune ittō kaji system, in which individual smiths worked alone, to mass forging by kōbō-sei workshops. In this period of transition, Kiyomitsu met the demands of mass production while keeping a high standard of blade-making, and he is counted among the representative smiths of Sue-Bizen.

Among Sue-Bizen works, Kiyomitsu's blades are characterized by particularly high-precision jigane and hamon. The jigane is well forged, showing itame mixed with mokume, and some works display faint utsuri. The hamon is suguha, and it is considered typical of Kiyomitsu to have ashi and yō within the hamon, with ko-nie on the nioiguchi.

The signature is usually cut as "Bizen no Kuni-jū Osafune Kiyomitsu." Works made to order also bear common names such as "Gorozaemon-no-jō" or "Magoemon-no-jō," and many works with a dated inscription survive. The overall form (taihai) centers on the practical uchigatana of the mid-Muromachi period, with a short nakago, shallow sori, relatively wide mihaba, and chū-kissaki, clearly showing the period characteristics of Sue-Bizen. Many works survive today, and in rankings of cutting performance, Gorozaemon Kiyomitsu and Katsubei Kiyomitsu are counted among the wazamono.