Nagasone Okimasa

Nagasone Okimasa was a swordsmith active in Edo, Musashi Province, in the early Edo period, commonly known as Shobei. He is said to have been either the natural son of, or a pupil later adopted by, Nagasone Okisato (art name Kotetsu), a master ranked Saijō Ōwazamono in Edo-period cutting-test rating books such as the Kaihō Kenjaku. According to Wikipedia, the touken-world.jp directory, and the Meitō Genso Jiten, Okimasa is thought to have assisted his teacher Okisato from the latter's days as an armorer, and his independent forging activity began in earnest mainly after Okisato's death in 1678.

The oldest of his dated surviving works is from 1673, and the latest from 1690; during this span he forged swords, wakizashi, and spears. He initially lived at the same address as his teacher, but records such as an entry in the 1697 Kokka Man'yōki suggest he had moved to Kanda by around this time. His signatures include "Nagasone Okimasa," "Nagasone Kotetsu Okimasa," and "Nagasone Kotetsu Nidaime Okimasa," though none bearing the specific character Okisato used for "Kotetsu" (乕徹) have been confirmed.

Okimasa's work shows a shallow curvature combined with itame-hada steel, tempering a juzuba-like gunome-midare or hiro-suguha, sharing many features with the style of his adoptive father Okisato; sunagashi is also noted in the steel.

Fewer of Okimasa's works survive compared to Okisato's, likely because he spent much of his time assisting his teacher's forging work rather than producing independently. Edo-period sword-rating texts placed him among the "highest-rank Shintō smiths" (Shintō Saijō-saku), and for sharpness he was ranked alongside Okisato at the very top tier, Saijō Ōwazamono — regarded as a smith whose skill rivaled that of the first-generation Kotetsu himself.