The ( Province) tradition emerged in the late period as one of the most technically sophisticated and influential schools in Japanese sword-making history. Founded by Kunimitsu—known as Kunimitsu—around the Einin era (1293–1299), the school pioneered revolutionary forging techniques that departed from earlier traditions. Kunimitsu's sons Kunishige, Kunihiro, and Kuniyasu continued his methods, though among surviving works only those attributed to Kunihiro can be confirmed upon inspection. The school's influence extended through the period and into the era, with later masters such as Sōmune and Sōsō working in the Bunmei period (1469–1487), demonstrating the tradition's enduring vitality even as supplanted the form.
blades are distinguished by their mastery of -based temper and profound steel activities. The typically exhibits dense , often with tendencies and occasionally admixture, characterized by thick adhering to the surface with vigorous appearing throughout. The school's signature achievement lies in the , where forms tightly controlled patterns—ranging from narrow with frequent to gentle mixed with , , and . What sets work apart is the richness and complexity of activities: , , , and appear with remarkable frequency, creating effects described as (running glue). The tends toward (tightness) while remaining (clear), and many works show extending the temper to the back ridge. In unsigned works, these combined features—thick adhering to both and , active , and frequent —serve as definitive markers of the school.
The school's technical innovations profoundly shaped subsequent Japanese sword-making, establishing standards of excellence that resonated through later periods. The tradition's emphasis on controlled activities and complex steel patterns became aspirational models for later smiths, including revival-period makers working centuries after the school's origins. During the mid- period, smiths such as Ippei Andai of Satsuma Province explicitly studied and emulated methods—particularly those of Norishige—creating works that, while designated as " tradition," demonstrated how the school's aesthetic principles could be reinterpreted in new contexts. The tradition's technical achievements in manipulation and steel refinement remain benchmarks against which Japanese blades are measured, with surviving works prized for their (sound and well-preserved) condition and the powerful, heroic presence created by the school's characteristic forging methods.