Izumi no Kami Kunisada signed himself, on a sword dated the eighth month of Genna 7, "Sesshu Osaka-ju Fujiwara Kunisada," and that one inscription fixes both the man and the moment: a -trained smith already settled in Osaka, at the founding of what would become the city's own tradition of swordmaking. Collectors call him Oya Kunisada, "Kunisada the Elder," and the published sources are explicit that the name exists to separate him from his heir, written that he is so called "to distinguish him from his adopted son, Inoue Izumi no Kami Kunisada" (養子井上和泉守国貞), the man later known as Inoue Shinkai. He was born in , went up to Kyoto, and is said to have entered the school of Kunihiro; but Kunihiro died in Keicho 19 when Kunisada was only twenty-five, and the judges read his early style and signatures as in fact following his senior fellow-disciple, Echigo no Kami Kunitomo. He moved to Osaka with Kawachi no Kami Kunisuke, received the title Izumi no Kami in Genna 9, took the tonsure in old age under the name Dowa, and died in Keian 5 at the age of sixty-three, "one of the pioneers who opened the path for the Osaka smiths" (大坂鍛冶の開拓者の一人).
His recognized hand is a broad, imposing in the Keicho- taste, wide in body with little taper from base to tip, thick in , and carried out to an extended or . The forging is , frequently mixed with and tending to stand a little, , with thick and entering freely; where the grain opens, the published sources name it the loose, vigorous texture of the school, the steel of his teacher carried into Osaka. This is the his work is read on. Over that he tempers a base into which he sets , and , the line opening from a short straight in the manner, deep in with well adhered, and running through it, often with and drifting . The runs straight into a or enters in with , turning back rather long or deep. On his finest blades he adds carving: a relief -no- dragon set within the groove, with a and paired goma-bashi, work the judges call distinctive and superb and count among his tells.
The is the steady base beneath the temper. with thick and frequent appears across his oeuvre, sometimes standing into that rustic surface, sometimes drawing tight; the deep, bright and the along the edge are constants, and the activity is carried in and , in and , rather than in towering clove heads. Where one of the 27th session widens and turns vigorous, the published sources find it "rather than resembling Kunitomo, his de-facto teacher, closer to the calm, unforced character of Kunihiro himself," naming the -sagari and the frequent as the elder Kunisada's own marks. The at times deepens, at times falls subdued, and that deliberate variation in how the gathers is itself part of his manner.
Three registers run through the work. The first is this prime over the bold . The second is a -leaning manner that looks back through his masters: the published sources read one as a -style piece made in emulation of his teacher, the not conspicuous yet the whole vigorous, and call a an emulation of Sadamune, written "modelled on the manner of Sadamune, and well made" (相州貞宗の風を模して出来がよい). The third is a quiet, bright of his late years, of which the judges note "the first generation's work, though skillful" (親国貞の直刃出来は上手ながら), survives in very few examples, and that such a blade "at a glance appears closer rather to that of the second-generation Shinkai" (一見してむしろ二代真改の作に近い). To these late years belong his cursive sosho signatures of the Dowa period, which the sources connect to his old age, when his second generation, Inoue Shinkai, is said to have served often as proxy in both forging and signing; whether a given cursive blade is the elder's own work or Shinkai's , and whether such pieces should be read as a separate second-generation Shinkai Kunisada, remain matters the published record leaves open for further study.
What sets him apart is named in his own designation papers. Against the tightly packed of the old and Yamashiro lines, his standing and his opening from a straight are the Osaka- signature, not a ; against his own son Shinkai's brighter, more refined steel, the elder's hand reads as the rougher, more vigorous root from which the Osaka tradition grew. The judges place him with Kawachi no Kami Kunisuke at the head of that movement, his de-facto teacher Kunitomo behind him and his master Kunihiro behind that, and his heir Shinkai carrying the name forward into its most celebrated generation.
For the collector he is a major Osaka- name held within reach but never common. Fujishiro grades him Jo-jo . He has no National Treasures and no Important Cultural Properties; his record runs instead through the rank in number, with three and several prewar Bijutsuhin, eighty-four blades standing in the and tiers. The provenance that survives is distinguished: blades that passed through the Imperial Family, the Sanada house, and the family of his native , with one Bijutsuhin now held at the Sano Art Museum. The published sources reserve their highest words for his signed , calling one "a quintessential work of the first-generation Kunisada, especially deep and splendid in , an outstanding example among his works" (初代国貞の典型作で殊に匂口が深く華やかで同作中傑出の一口), and another, the -flavoured , simply "a blade after the elder Kunisada's own heart" (親国貞会心の一口). Most of these are held rather than traded, and only a handful of the and blades change hands in any decade; a signed Oya Kunisada in good condition comes to a private collector from time to time, with patience, and is a substantial acquisition when it does, a document of the founding of Osaka steel.