Kunimasa was a disciple of Kunihiro, the foundational master of the early movement in Kyoto. Regarding his personal details, Ichiran states only that "he signs with two characters" and that he was "a disciple of Kunihiro," and no other recorded accounts survive. However, there remains an work by Kuniyasu upon which Kunimasa inscribed "Kuniyasu shosaku, Kunimasa," indicating that compared with Kuniyasu and others, he was a junior member within the circle. While Kunihiro was alive, Kunimasa was likely among those who acted as substitute makers forging on his behalf. This is supported by the fact that extant signed blades are remarkably few, that his workmanship closely resembles Kunihiro's, and that details of the tang construction -- including the tip, , and the bold two-character signature cut with a thick chisel below the toward the -- are entirely the as those seen on signed works by Kunihiro. There is also a theory that a second generation later moved to , which may account for occasional misattribution to the Hojoji group.
The forging across Kunimasa's surviving works displays mixed with , with the grain standing up and presenting the rough, texture characteristic of works. Fine adheres well in a minute sprinkling, and fine enters, producing a that in the finest examples is bright and clear. The is chiefly mixed with -- a pattern seen from time to time among his works and perhaps representing a personal hallmark. The is deep, adheres well with some coarser mixed, and run through the hardened edge, and slight enter. The typically runs with , sometimes showing slight . In his finest surviving piece, a in on the and on the , both the and are bright and clear, and the -- including a , , and Bishamon- -- are executed splendidly.
Though Kunimasa is a smith of exceedingly few extant works, the quality of his surviving blades places him among the first-rate craftsmen within Kunihiro's circle. His works clearly express characteristics in the distinctive texture, the diagonal rising from just above the , and the -tendency , as well as in the tang construction and signature manner. In view of the existence of works of such caliber, he merits recognition as a highly skilled member of this celebrated school.