The school was founded by Kunihiro, originally a warrior of the clan of Obi Castle in Province, who after his lord's fall traveled through various provinces refining his craft before settling permanently at Ichijo in Kyoto from Keicho 4 (1599) onward. There he trained many outstanding disciples, elevating the renown of "-mono" and establishing one of the most influential workshops of the early period. Many of his followers -- Masahiro, Kuniyasu, Kunitomo, Kunitsugu, Hiroyuki, and Kunimasa among them -- were themselves natives of who followed their master from Obi to the capital, forming a tightly knit provincial cohort that transplanted itself to the cultural center of Kyoto. After Kunihiro's death in Keicho 19 (1614), the school's influence radiated outward: Kunisada and Kunisuke relocated to Osaka and became pioneers of the Osaka tradition, while Kunimichi remained in Yamashiro as the foremost inheritor of the manner, and Kunikiyo carried the lineage to .
The school's collective technical identity is anchored in the distinctive texture -- a rough, boldly standing mixed with and , with thick adhering and frequent entering the ground. This coarsely textured forging is the most immediately recognizable hallmark of production, appearing with remarkable consistency across the school's members from Kunihiro himself through Kunimichi, Kuniyasu, Masahiro, Hiroyuki, Kunimasa, and Hirozane. The is characteristically built upon or shallow mixed with , , and pointed elements, with deep , thickly adhering , and conspicuous and running throughout the tempered area. A subdued showing a tendency is consistently identified as a distinguishing hallmark of the group. The typically enters and ends pointed with vigorous . In the finest works, conspicuously coarser emerges in the upper half, with and producing scenic effects that convey an impression of antiquity. A diagonal rising from below the is recognized as a habitual trait shared by multiple members. The school's broad aspiration was the emulation of the superior - masters -- above all and Sadamune -- yet within this shared ideal, individual members developed distinct registers. Kunihiro's mature Keicho-uchi present the full -modeled manner; Kunimichi produced the most flamboyant with bold patterning; Kuniyasu's forging is described as the most conspicuously standing and rough within the group; Masahiro's tempering is the most restrained and closest in character to the master's own; and Kunitsugu and Kunitomo retained a pronounced coloration suggesting Izumi no Kami Kaneyuki and the late-Seki mode as models.
The school's historical significance is threefold: it revived the -laden, boldly textured aesthetic of the medieval masters during the and early periods; it served as the direct progenitor of the Osaka tradition through Kunisada and Kunisuke, whose and brilliant decorative tempering transformed the art of the early modern sword; and its workshop practices -- the system by which senior disciples such as Kuniyasu, Masahiro, and Hirozane produced work on Kunihiro's behalf -- illuminate the collaborative nature of pre-modern swordmaking ateliers. The has assessed the finest works by members such as Kuniyasu as "comparable in quality to Kunihiro's masterworks," while Kunimichi's bold -laden tempering is recognized as fully capturing the spirit of the -influenced manner. The range of the school's output -- from Ariyoshi's earliest transitional piece of Keicho 2, through Kunihiro's celebrated Keicho-uchi, to the refined Osaka-period brilliance of the Kunisuke lineage -- encompasses one of the broadest and most consequential artistic trajectories in swordmaking. Collectively, the school's members produced a body of work characterized by bold conception, vigorous internal activity, and a distinctive rustic vigor that the consistently identifies as among the finest achievements of the early period.