Nobukuni Yoshimasa I

Nobukuni Yoshimasa I was the son and successor of Nobukuni Yoshisada, who founded the Chikuzen Nobukuni school. Born in the late Sengoku period, he relocated from Buzen Province to Chikuzen in 1602 at age 26 alongside his father, and began independent sword production around 1611 as a retained smith of the Kuroda clan.

In 1613, at Kuroda Nagamasa's command, Yoshimasa traveled to Bizen Province to study under a smith of the Yoshioka Ichimonji school — an experience that decisively shaped his mature style. This Bizen training infused his work with a deep nioi-based choji or gunome-midare that distinguishes the best Chikuzen Nobukuni blades from typical Yamashiro Nobukuni pieces.

His blades display the characteristic Chikuzen Nobukuni aesthetic: vigorous nie along the edge with frequent kinsuji, active gunome or choji hamon, and a dark, robust jihada with flowing itame influenced by Bizen practice. A work recognized as his finest surviving piece is held in the permanent collection of the Kitakyushu Museum of History and Folklore (exhibit ID 3706), where it is presented as "the finest surviving example of Chikuzen Nobukuni Yoshimasa."

His son (or successor) Nobukuni Yoshimasa II became one of the leading smiths of the Kanbun-Enpo shinto golden age (1661–1680), carrying the Chikuzen Nobukuni tradition to its peak. Yoshimasa I holds a Josaku ranking and is counted as the key figure who established the distinctive Chikuzen Nobukuni style that defined the school through the Edo period.