Rai Kuniyuki was, in the words the published sources return to again and again, the de facto founder of the Rai school of Yamashiro, working in the mid Kamakura period. None of his own blades carries a production date, but the two-character Kunitoshi, transmitted as his son, left a tachi dated Koan 1 (1278), and on that footing the published sources affirm the usual reckoning that places Kuniyuki around the Shogen and Bun'o years. He stands at the head of the line the late-Kamakura Yamashiro tradition would be built upon, and his signed tachi survive in comparatively large numbers while a single reliable tanto is all that is known, exactly as for that same Kunitoshi.
The shape of his tachi is not one thing. The published sources describe a range that runs from slender, orthodox builds to broad, powerfully made blades, with the point typically tied off in an ikubi manner. The signed, ubu pieces keep a high, wheel-like curvature and a small point of real grace; the great mass of the surviving work is o-suriage and unsigned, wide in the body with a thick kasane, and even after shortening it holds a deep wazori and a weighty, dignified bearing that reads at once as mid Kamakura.
The jigane is the constant. It is a finely forged ko-itame, at times carrying itame, mokume and a little nagare-hada, worked until it is dense and refined; over it the ji-nie lies thickly in minute particles, fine chikei enter, and a nie-utsuri rises that in places shades toward a midare-utsuri. The steel is strong and clear, and the bright, refined forging that the connoisseur reads as Rai-hada is the first thing the eye should settle on. This is the calm, lustrous jigane on which everything else is staged.
Over that jigane Kuniyuki tempers a wide, suguha-toned ha rather than the full choji of contemporary Bizen. Into it he mixes ko-choji, ko-gunome, small midare and squared-off elements, so that the temper is complex and changeful without ever becoming a clamorous midare; ashi and yo enter densely, often as the Kyoto-style saka-ashi, the nioiguchi runs deep and bright, ko-nie attaches thickly, and kinsuji and sunagashi move through the body of the ha. At the crests of the undulations small tobiyaki and yubashiri sometimes gather into a kiji-mata or gan-mata figure, and muneyaki may appear above. It is a temper of restraint and activity at once, the activity carried in the nie rather than in the height of the pattern.
The boshi is where his hand is most easily misjudged. It is not a plain ko-maru. A ko-maru is indeed the most frequent turnback, but it is most often drawn out by hakikake, the brushed nie of the point continuing the work of the ji below; the published sources describe a boshi that vigorously brushes[[c:1]] and that turns back in a small round with a slightly pointed tendency[[c:2]]. In many blades it falls into a midare-komi with a pointing tip[[c:3]], at times genuinely pointed, at times burned through in a yakizume manner. A reading that names only the small round and the irregular turnback misses the swept tip that is in fact the dominant feature, and for recognition the hakikake belongs in the first rank of his boshi traits beside the ko-maru itself.
For a founder of his rank the named histories are heavy. A signed Tokubetsu-Juyo tachi descended in the Kuroda family of Chikuzen and carries an origami of Genroku 14 (1701) by Hon'ami Kochu[[c:4]] valuing it at one thousand kan, with Goto fittings on its tachi mounting; another o-suriage blade passed through the Shimazu family of Satsuma; signature variants are read against a piece formerly in the Ogasawara collection, and his blades reach into the Tokugawa houses as well. His work numbers a National Treasure and many Important Cultural Properties, and within the published catalogues his Tokubetsu-Juyo and Juyo entries together run to roughly a hundred, a count that places him among the very highest of the koto Yamashiro masters and makes a freely tradeable example a genuine rarity.
