The Kunikane was born Hongō Genzō in Bunroku 1 (1592) at Kokubun-Wakabayashi in Sendai, Mutsu, and entered the service of Date Masamune as a retained smith. By his lord's command he went up to Kyoto and studied under no Kami Masatoshi; in Kan'ei 3 (1626) he received the court title Yamashiro Daijō, and he styled himself a descendant of the later line of Yamato Hōshō Gorō. In the opening decades of the period, when the manner in and was the fashion of the day, Kunikane gave his working life to reviving the -forging, -tempering Hōshō- of old Yamato. The published sources record that 「作風は一貫して大和保昌伝に終始し」, his manner kept to the Yamato Hōshō tradition from first to last, and every blade of his on the designation record is signed in his own name.
His characteristic hand is constant. The forging is a tightly packed , at times running into , carrying fine thickly applied and frequent , the steel notably clear. A often rises from below the , and the published sources name it a personal habit of the smith, calling it on one a feature that 「初代国包の手くせといえる」. Over that he tempers a or , frequently broad and shallow in , the deep and bright. The activity is the Yamato kind: general along the , and set freely into the line, , and uchi-noke mixed in, and entering.
Fine and abundant over a clear, well-packed recur on nearly every blade, the forging growing more refined as it tightens. The is the Yamato finish, running straight into a -like point with vigorous . On this point the published sources are unusually candid. Measured against the early Hōshō, they say his shortfall lies in 「物打上の変化に乏しいことと、帽子が平凡な点にある」, a relative want of variation above the and a commonplace , while holding that the and of his representative dated are nonetheless excellent.
One consistent hand divides into two registers by the shape it takes. The standard work is the , and long-signed, very often dated, with a high , shallow and an elongated ; his dated of Kan'ei 4 and Kan'ei 9 are the reference points for his work. Two prewar carry his go in the signature: one signed Yamashiro Daijō Fujiwara Yokei Kunikane and dated Keian 1 (1648), with a high -zori, , a slightly standing and a of in a shallow with , the other signed Yokei Kunikane over a clean . The rarer register is the , of which the published sources note that very few survive. On these the temper opens out: the upper half takes a broader , the thickens and coarsens in places, resembling appear and the tends toward , while the carvings, a and a with , are cut deep in the manner of old Yamato work. Of the Onikiri the published sources say that in it 「初代国包の本領が遺憾なく発揮された」, his true strengths brought out without reserve.
His bright and Yamato set him apart from the -fashion smiths of his day, and his disciplined over a clear separates him equally from the Hōshō he revered, whose and the texts say he did not quite equal. He retired in Shōhō 2 (1645) and handed the headship to his eldest son Kichiemon, the second-generation Yamashiro no Kami Kunikane, founding a Sendai Kunikane line that carried the Hōshō- to the end of the period; the remains the standard against which the later generations are judged.
His designated record runs through one Important Cultural Property, four prewar , one and twenty-eight blades, with one sword recorded in Honma's inventory of the Imperial collection, thirty-five designated works on record and every one signed. There are no National Treasures. His finest, an , signed and dated preserved in its original form and held in the Uwajima Date family, the published sources call 「古保昌に優るとも劣らぬ作域」, equal to or surpassing the old Hōshō, and a masterpiece of imposing presence. Provenance runs through the houses he served and a few long-private hands: the Date and the Uwajima Date families above all, and named collectors such as Kimura Sadazō. A signed Kunikane is not beyond a serious collector's reach in the way a great master is, yet his blades are mostly held rather than traded, the rarest of all, and a dated example in good state comes to market only from time to time.