Osafune Chōgi

Osafune Nagayoshi (長船長義) was a swordsmith who worked in Osafune, Bizen Province (present-day Osafune-chō, Setouchi, Okayama Prefecture) during the Northern and Southern Courts period. He signed his works "Nagayoshi" and is also read as "Chōgi." His period of sword-making was the latter half of the fourteenth century, centering roughly on the Jōji and Ōan eras, which falls within the mid-Northern and Southern Courts period. Within the Osafune school, which formed the mainstream of Bizen swords, Nagayoshi constituted a separate lineage from the direct line continuing from Mitsutada, Nagamitsu, Kagekō, and Kanemitsu, establishing his own distinctive style by incorporating the Sōshū tradition strongly. He was later counted among the Masamune no Jittetsu (Ten Disciples of Masamune), and as a representative figure of Sōshū-tradition Bizen work, he was celebrated alongside his contemporary Kanemitsu as one of the two greatest masters of Northern and Southern Courts Bizen. He headed his own school and is positioned as the founder of the Nagayoshi school.

His style is characterized by the bold and magnificent tachi form of the Northern and Southern Courts period, with broad width and large kissaki, which is his forte. The jihada is itame with strong ground-nie, and many examples are notable for their lack of prominent mirror-like reflection (utsuori). The hamon is based on notare with gunome interspersed; he forged rich variations such as large gunome with open hips and ear-shaped disorderly hamon with two gunome arranged in pairs. The nie is thick, and within the blade prominent kinsuji and sunagashi are clearly evident, with both ash and leaf-like patterns well-developed. The point structure is disorderly and sharp-pointed in its return, with many examples displaying deep returns. The true essence of Nagayoshi lies in fusing the jihada of the Bizen tradition with the boiling action of the Sōshū tradition, and he is evaluated as "the most un-Bizen-like swordsmith working in Bizen."

As examples of surviving signed works, the Important Cultural Property "Blade, Signature Nagayoshi" (inscription ellipsized) is housed in the Tokugawa Art Museum, Nagoya. This work originally lost its signature through reshaping (suriage), and the unsigned blade received a long supplementary signature cut by Horikawa Kunihiro in Tenshō 18 (1590) at the request of Nagao Akeinaga, a military commander of Shimōtsuke. It is known as a representative example with broad width and magnificent form, featuring rectangular, evenly aligned disorderly hamon. Additionally, the Important Cultural Property "Tachi, Signature Bizen Osafune Nagayoshi" is housed in the Kanisenō Foundation (Yamagata Prefecture). It features small itame with finely boiled jihada, a hamon with gunome-disorderly interspersed with notare, showing ash and leaves well-developed with deep nioi and small nie interspersed, and the point structure is disorderly and sharp in its return. Surviving tachi signed by Nagayoshi are few, making this a precious reference work.

Nagayoshi is counted along with Kanemitsu among the master swordsmiths representing Northern and Southern Courts period Bizen, and the two are often cited together as "Kanemitsu and Nagayoshi." Through the refinement of technique and brilliant hamon work, in contrast to Kanemitsu's serene approach, he is evaluated as having a vigorous, masterful style, and is highly valued for his distinctive approach that fully assimilated the Sōshū tradition. Heading a group of disciples, he formed the Nagayoshi school, and in later generations many copies emulating his style were produced. In terms of sharpness, he is positioned in the upper rank and is esteemed by later generations as an exceptional master swordsmith.