Horikawa Kuniyasu signed only the two characters of his name, never a court title, and within the whole Horikawa school he alone cut his file marks in reverse. These two habits, more than any single feature of forging or temper, are how the published sources tell him apart. The Tanaka genealogy gives his common name as Saburōdayū and records that he was the youngest brother of Horikawa Kunihiro; other sword books make him instead a nephew, originally from Obi in Hyūga, who admired Kunihiro, traveled up to Kyoto, entered his gate and there matured. He worked in the Keichō years, at the opening of the shintō age, and his record is one of the closest in the school to its founder.
The published sources return again and again to a single explanation for how few of his signed blades survive. His manner of forging, the construction of his tang, and the cut of his signature so closely resemble Kunihiro's that he is thought to have served as one of his daisaku, the substitute hand producing work under the master's name. The first-session Jūyō commentary puts it plainly: among signed blades that survive, those bearing Kunihiro's own signature yet judged on appraisal to be wholly Kuniyasu's hand are not few. He is, in effect, the daisaku whose work stands closest of all to Kunihiro's, and the small body of pieces signed Kuniyasu is what remains once the blades that went out under his brother's name are set aside.
His characteristic hand copies the higher Sōshū masters, and within them the Naoe-Shizu manner above all, what the commentaries call 「彼が最も得意とした志津風の作域」[[c:1]], the Shizu-style range in which he most excelled. The jigane is the constant. Over a board-grain itame mixed with mokume, and at times ō-itame, the grain stands up into a coarse, dry texture the published sources name the most conspicuously standing zanguri in the whole Horikawa group and a distinctive trait of this smith; fine ji-nie sets densely and rather thickly, chikei enter well, and on several blades a diagonal mizukage rises from below the machi. The carvings run to the devotional, futasuji-hi with bonji, rendai and kuwagata, suken, gomabashi and kurikara, executed in relief and harmonizing with the wide, forceful Keichō shape.
Over that jigane he tempers a shallow, large notare into which gunome, ko-gunome and angular, squared-off elements gather, ashi entering, the nioi deep and the nie thick. The nie is the point the published sources name as his recognition: at times it coarsens and gathers in uneven clusters, hotsure breaks along the edge, sunagashi runs broadly, long kinsuji enter, and small yubashiri and tobiyaki are mixed in, while the nioiguchi inclines to shizumi, a subdued, slightly sunken line the commentaries read as a mark of this group. The boshi enters in notare or midare and turns back in ko-maru or yakizume with vigorous hakikake. Against this bold, rustic prime stands a rare second register: on one Jūyō wakizashi he tempers instead a chū-suguha with places of shallow, small notare, the nie not coarsened as usual but composed quietly in ko-nie. The published sources call examples of his suguha rare, judge this one finished with consummate skill, and liken it to 「同派の平安城弘幸を想わせる」[[c:2]], the work of Heianjō Hiroyuki of the same line.
What singles him out in the school is not chiefly his style, which is by design close to his master's, but two technical habits the commentaries name as his great points of connoisseurship. He signs only the two characters Kuniyasu and never took a court title, 「銘字は必ず二字銘にきり, 受領銘はない」[[c:3]], the only one among the superior Horikawa smiths to receive no juryō. And alone in the school he cuts his file marks reverse, 「一門中, 鑢目が逆筋違」[[c:4]], said to be because he was left-handed, a feature the published sources note does not appear on the blades signed Kunihiro. The same commentaries connect his two-character work in both style and signature to Kunitsugu, transmitted as his elder brother, and observe that within the Horikawa group no one but Kuniyasu produced the kiriha-built Sadamune-style copies seen among his work. From the manner of his forging and temper they read him as one who took the orbit of Sadamune for his model, 「おそらく国広の代作に任じていたためと思われる」[[c:5]], and so served the master's name with his own hand.
For the collector he is a rare and rewarding name. Fujishiro grades him Jō-jō saku. He has no National Treasures; his record runs instead through one Important Cultural Property, a katana held in the Tokyo National Museum, a wakizashi at the Tokubetsu-Jūyō rank, a prewar Jūyō-Bijutsuhin katana once owned by Jinbei Kashiwara of Osaka, and some fourteen Jūyō blades, one of them transmitted in the Shimazu family, lords of the Kagoshima domain. The published sources call his finest pieces masterworks that bear comparison with Kunihiro's own, one first-session blade praised as 「国広の傑作に比肩する出来映えで, 同作中傑出した一口である」[[c:6]], comparable in quality to Kunihiro's masterworks and outstanding among Kuniyasu's oeuvre. Because so few signed works exist, and because most designated blades are long held rather than traded, a signed Kuniyasu comes to light only seldom; a privately held example is a notable thing for a collector to encounter, and it carries the added interest of a hand that, in the world at large, is hidden inside the signed work of Kunihiro himself.
