The Saburo Kunimune school gathers a small group of - smiths of the Naomune line (直宗系), worked in the province of and reaching its head in the middle period. The line descends from the and Ko- smith Naomune through Kunizane to the Kunimune group, whose principal figure, called Saburo, the published sources place around the Shogen years (about 1259). Though the house resided at , the texts keep it clear of the mainstream that descended from Mitsutada, reading its line and its metal as to the last. The members carry an old account of Kunimune's career: that the regent Hojo Tokiyori summoned him east to , where, with Sukezane of the Fukuoka- school and Kunitsuna of the school of Kyoto, he became one of the pioneers of swordmaking (相州鍛冶), so that the Naomune line stands at the join of and the rise of -. Beside Kunimune the members name Kuniyasu, recorded as the fourth son (the Shiro of the house), and Nakahara Kunimune, transmitted as a pupil of the first generation, whose dated remains run through the late years.
The shared vocabulary the members describe is a manner built over a standing grain. The forging is an mixed with that tends to rise, with gathered on the surface and fine working through, over which a bright appears. Within this base the school divides into two hands, and that division is its spine. The flamboyant hand is a wide, powerful , often with high and , tempered in a -led crowding with , angular pointed teeth, and entering richly, the laden with and and running through; its keyed feature is the whitish stain known since old times as the Saburo no shirajimi (備前三郎の白染み), which shows within the . The quiet hand is a slender or ordinary-width, gentle , the forging tighter to a fine with minute , the temper a mixing and with and slanting , the tight with . Across the school a softer divergence recurs: the sinks and clouds to in places, a quality the texts read together with the shirajimi; the members single out this clouding in Kuniyasu's with its as the mark of his hand. Nakahara Kunimune's late hand inclines further toward an temperament (-kishitsu), his base carrying a stepped where suji- and overlap.
For the is the working tell in the quiet hand. A calm Kunimune in may at first recall Sanenaga or Kagemitsu of , yet the members mark the difference at the turnback, where the rises straight and returns in a large round , the -laden and and prominent completing the judgment. At the flamboyant top end the confusion runs instead toward , and there a opening in the with clotting even inside the settles the attribution; that -open manner marks the small sub-group of the Tenkyuwari look, an anchor for blades of the air. The shirajimi is a keyed feature rather than a constant, frequent in the flamboyant works and little seen in the -toned make. The breadth of the two manners and the late dates lead the texts to judge that the name was probably not the work of a single generation, a point left for further study. Kunimune stands at the head of the group, ranked Sai-jo in Fujishiro's grading; his signed work is headed by the Terukuni Jinja of Kagoshima, and the named blade Tenkyuwari carries one of the great sword histories, worn by Uesugi Kenshin at Kawanakajima, given to Satake Yoshishige and held thereafter in the Satake house of Kubota in Dewa with an - of Kansei date. The Uesugi, Satake and Shimazu, the Kishu and Owari Tokugawa, the Ii and Abe houses and the Imperial Household appear among the recorded owners, and one Nakahara Kunimune likewise passed in the Satake family, the master whose journey east stands behind the rise of .