Kunimune, celebrated under the appellation " Saburo," was a swordsmith of the Naomune lineage resident at in Province. He was the third son of Kunizane, himself the son of Naomune, and his line of descent was distinct from that of Mitsutada. According to longstanding tradition, Kunimune was summoned by Hojo Tokiyori of the shogunate and, together with Sukezane of the Fukuoka group and Kunitsuna of Kyoto, became one of the pioneers who laid the foundations of () swordmaking. Nevertheless, throughout his career he adhered strictly to the tradition, and no works attributable to him in the manner are known. A second generation is recognized on the basis of extant bearing date inscriptions from the Showa era (1312--1317), and from both the breadth of stylistic variation and these chronological considerations, the question of whether the name encompasses more than a single generation has long been a subject of scholarly inquiry.
Works by the first-generation Kunimune are encountered in comparatively large numbers and may be broadly divided into two groups. The first comprises powerful of wide bearing flamboyant in a -dominant style, with signatures that are large, cut with a thick chisel, and rounded in character-form; these works display mixed with , prominently standing , and rich internal activity including , , , and . A characteristic long noted in these works is the appearance within the tempered area of staining described from olden times as "the white of Saburo." The second group consists of more slender, gentle forms tempered in calm, -leaning patterns, with signatures that are smaller, cut with a finer chisel, and more angular in character-form. Compared with works in general, Kunimune's blades tend to show , and all share in common an . The second generation, by contrast, excels in a fundamentally temper with a tightened , mixed with and ; the manner of signing likewise differs, with the character elongated in form and cut with a fine chisel. The second generation's inscription " no ju " is considered significant in overturning the theory of relocation to Province.
Across the corpus of designated works, the consistently praises Kunimune's blades for displaying the distinctive character of the smith in both and , and the condition of preservation is frequently described as -- sound and well-preserved in both and . Works by the first generation are valued for restraining excessive undulation while tempering a variety of forms and displaying rich internal activities, fully bringing Kunimune's individual qualities to the fore. The breadth of his stylistic range, encompassing both flamboyant and refined , is itself regarded as a defining attribute. As one of the acknowledged pioneers of swordmaking who yet remained faithful to the manner, Kunimune occupies a singular position at the intersection of these two great traditions, and his works are prized for the quality of their craftsmanship and the historical weight of their provenance.