The tradition originated in , Province, during the late period, founded by Kunimitsu, who built upon an -derived foundation of refined forging and tempering. By laying more thickly across both and and giving pronounced expression to and , Kunimitsu established the technical vocabulary that would define the school. Under his tutelage, three exceptional talents emerged — Yukimitsu, Masamune, and Norishige — who, through mutual refinement as fellow disciples, brought the tradition to completion. Masamune, whom the places "at the very summit," carried the manner to its ultimate expression, while Norishige developed a powerfully individual forging texture in Province, and Yukimitsu preserved the closest continuity with Kunimitsu's restrained foundation. From Masamune descended a second generation of masters — his adopted son Sadamune, Go Yoshihiro of , and Kaneuji of — who carried the aesthetic into new provinces and new expressive registers. The later -period smiths Hiromitsu and Akihiro, working in as successors to Sadamune, extended the school's lifespan deep into the fourteenth century.
The technical hallmarks that unite the school across its generations are a forging of mixed with , upon which exceedingly fine adheres thickly and enters with great frequency, producing steel of exceptional clarity consistently described as "bright and luminous." The is characteristically founded upon , mixed in varying degrees with , , and , with deep and thickly adhering from which and run with conspicuous frequency. and appear along the , and the is invariably praised as bright and clear. Within this shared vocabulary, the school's internal evolution is legible: Kunimitsu's restrained , rich in likened to "an old man's whiskers," gave way to Masamune's explosive manner — compared in official records to sansui (splashed-ink landscape painting) — in which "gathers, thickens, and congeals" and "leap and move incessantly." Sadamune inherited this manner yet tempered it toward greater composure, producing a "calmer and more gentle" expression, while Go Yoshihiro achieved the highest degree of crystalline luminosity within the tradition. Norishige pursued a divergent path, his bold ("pine-bark grain") and somewhat dark, 'a-iro steel tone reflecting the forging character of the northern provinces. In the period, Hiromitsu and Akihiro brought the school's final innovation: the deliberate orchestration of (full-temper) through unified , , and flamboyant incorporating the distinctive round-headed clusters known as dango-choji. Kaneuji represents yet another axis of variation, combining vigor with a Yamato temperament expressed through flowing -inclined forging and vigorous in the .
The school's historical significance is singular within the Japanese sword tradition. In Masamune, it produced the smith universally acknowledged as having elevated the artistic quality of the Japanese sword to its highest plane — an achievement framed in official records not merely as technical mastery but as an aesthetic breakthrough of civilizational consequence. Sadamune "most faithfully inherited his master's manner" while establishing an individual identity through refined restraint and distinctive carving. Go Yoshihiro, despite the complete absence of signed works, achieved recognition at the highest levels of official designation through the unmistakable individuality of his luminous, poised aesthetic. Norishige's became one of the most celebrated forging textures in the entire canon, while Yukimitsu's intimate connection to the Kunimitsu foundation preserved the school's lineage. Hiromitsu and Akihiro's perfection of tempering established a paradigm that exerted lasting influence on swordsmiths across multiple provinces and centuries. Through peripheral masters — in , Go Yoshihiro in — the aesthetic radiated outward from , fundamentally reshaping sword production throughout Japan. The school's members collectively account for many of the most celebrated blades recorded in the Kyoho -cho and preserved in the great collections, a concentration of masterworks that attests to the enduring preeminence of the tradition within the hierarchy of Japanese swordsmithing.