Kunihiro was originally a warrior in service to the clan of Obi Castle in Province. After that house fell, he traveled through various provinces, refining his swordmaking skills while producing blades in different regions. He received the court title Shinano no Kami and, from Keicho 4 (1599) onward, settled permanently at Ichijo in Kyoto, where he trained many outstanding disciples and elevated the renown of "-mono." He is said to have died in Keicho 19 (1614). His workmanship is broadly divided into two types: works produced before his settlement at — the so-called Tensho-uchi — sometimes display the style of late or late Seki, while works made after settling — the so-called Keicho-uchi — differ markedly in manner and many appear to have taken as their model the superior craftsmen of the tradition.
The Tensho-uchi characteristically exhibit a late--style temper, with forming strongly and rougher mixed in, and at the boundary the suikage stands out; the carvings — including the distinctive Daikokuten motif — are often among the most meticulous executed by this smith. The Keicho-uchi, by contrast, present the rough, so-called skin character that is distinctive to work: mixed with , the grain standing out, with thick and frequent . The typically forms a shallow mixed with , with deep and thickly adhering ; and appear throughout, and the is bright. The enters and ends pointed with vigorous . In certain masterworks, conspicuously coarser emerges in the upper half, with and occurring, while the width of the displays alternations of broad and narrow — a hallmark of the manner. The below the , recognized as one of his habitual traits, frequently appears in his post-settlement works. At their finest, these blades present an appearance suggestive of old work yet retain unmistakable characteristics of Kunihiro's own hand — the boldly textured forging, the -rich interior, and the subtle charm of .
Kunihiro is celebrated not only as a technically outstanding smith but as one of the foremost masters of the early period, having trained many excellent disciples and thereby founding the school. consistently describe his finest Keicho-uchi as works that "present a typical yet particularly outstanding example" in which both and display qualities recalling the joko of — above all suggestive of Sadamune. Several pieces are praised as demonstrating "the very best level of workmanship" and standing "among the finest achievements by Kunihiro." His collaborative work with smith Daido constitutes valuable material through which his movements before settling in Kyoto can be discerned. The recurrence of evaluative language such as "masterful blade," "excellent piece," and "outstanding example" across his designated works affirms Kunihiro's place as a smith of the highest rank — one whose combined mastery of archaic modeling and vigorous, powerfully expressive forging produced a body of work of exceptional scholarly and documentary value.