Sa Kunihiro was a swordsmith of the Nanbokucho period belonging to the Samonji lineage of Chikuzen Province. The Sa school flourished greatly during this era and produced numerous accomplished smiths, each contributing points worthy of note to the tradition. Within this prolific group, Kunihiro occupies a recognized position: several extant signed mei wakizashi confirm his identity, and his name serves as the standard attribution when certain qualities are present in unsigned works of the school. His activity is situated squarely within the era of expansive Nanbokucho blade production, and his works share the broad formal vocabulary of the Sa group while exhibiting an individual temperament that NBTHK appraisers have identified as distinguishable from his peers.

The technical hallmarks by which Kunihiro is identified within the Sa group center on a characteristic moist, soft quality — urumi — pervading the hamon, and a somewhat vigorous overall construction. The forging shows itame-hada mixed with mokume, the grain tending to stand out (hada-dachi), with ji-nie adhering and chikei entering frequently. The hamon ranges from ko-notare mixed with gunome to larger midare patterns in gunome with tobiyaki; sunagashi runs freely and kinsuji intermix, while nie adheres well and clusters of ara-nie may appear in places. The bosshi characteristically rises — a tsukiage tendency — becoming sharp and pointed with hakikake, a feature that, even within the broader Sa group, is appraised as pointing specifically to Kunihiro. Blades in full Nanbokucho form display wide mihaba, shallow sori, and o-kissaki, often with mitsu-mune construction.

NBTHK assessors recognize Kunihiro's works as powerfully constructed — goso — with well-executed jihada and hamon. Yet appraisals also note a candid assessment of his position: while the overall characteristics of the Sa group are pronounced, there are many works for which the individual personalities of the swordsmiths are not clearly distinguishable, and Kunihiro's workmanship in ji and ha is described as straightforward and ordinary — jinjo — in character. It is the convergence of the urumi quality, the vigorous deki, and the rising bosshi that permits confident attribution, marking Kunihiro as a steady and capable hand within one of the Nanbokucho period's most consequential sword-making lineages.