Kuninaga is the smith the published sources call Nakajima Rai, a pupil of Rai Kunitoshi who left Yamashiro and settled at Nakajima in Settsu, carrying the Rai manner forward into the Nanbokucho period. The Meikan records two generations of the name, placing the first about the Gentoku era at the close of Kamakura and the second about the Shohei and Oan eras; only the three-character signature Rai Kuninaga (来国長) is known, and not a single dated work survives. From this scarcity grows the central scholarly fact about him: the published commentary holds that he resembles Rai Kunimitsu while falling slightly short of him, and it makes the Nakajima Rai attribution itself a standing question of connoisseurship rather than a settled record. His jigane, his quiet temper, and a signature that comes in one form alone are what the judges read him by.
The constant of his work is the jigane. Over a well-forged itame he mixes mokume and a flowing nagare-hada, the grain tending to stand a little, hada-tatsu, with thick ji-nie and frequent bold chikei. His is a faint utsuri or a quiet nie-utsuri standing on this open, standing grain, the steel a step away from the closely packed jigane of the Yamashiro Rai mainstream. That standing itame is the feature the judges mean when they place him just below Kunimitsu; it is also, by their own account, the basis of the attribution problem. Examining his mumei katana, one of them writes that the Nakajima Rai kiwame has from old times been directed to suguha works of somewhat lesser technical level than Kunimitsu, and asks whether the convention is sound: 「やや技術が劣る直刃出来の作をそれに当てている事が, 果して妥当なりや否やという問題に始まる」[[c:1]] (the matter begins with the question of whether it is right that suguha works of somewhat inferior technique have been assigned to him). For the present, the commentary follows tradition.
Over that jigane his temper stays calm. The characteristic line is a suguha-toned or medium suguha into which ko-gunome, ko-choji and a shallow notare enter, with ashi and yo, ko-nie well adhered, and kinsuji and sunagashi running through, the nioiguchi now tight, now bright. The boshi runs straight to a small ko-maru, or sweeps with hakikake to a slightly pointed turnback. This restrained register, not the flamboyant choji of a Bizen hand, is the Rai inheritance he carries; and the published sources note that the first generation in particular was proficient in suguha, 「初代は直刃を得意」とした[[c:2]]. It is the steel and this quiet edge, taken together, that the judges weigh against Rai Kunimitsu, finding the resemblance plain and the refinement a degree less.
The record divides cleanly along the line of signature and form. The body of it is the o-suriage, mumei katana attributed to Nakajima Rai, wide in body with a chu-kissaki over the standing itame, the temper a broad or medium suguha, often carved with a plain bo-hi. The signed pieces, encountered only from time to time, are the work of the second generation in hira-zukuri with mitsu-mune, wide and slightly elongated with a thin kasane, the three-character signature cut large below the mekugi-ana. The published sources draw a distinction within his own work: the first generation was the suguha hand, while in the second 「二代にはむしろ直刃の作は少なく」[[c:3]], more irregular notare tempering becoming common. The signed wakizashi and tanto keep a consistent carving habit, a suken on the omote and gomabashi on the ura, each with a tsume beneath, a devotional program that sets them apart from the grooved mumei blades.
One piece stands outside every part of this account. A Tokubetsu Juyo wakizashi, signed by kinzogan-mei, breaks the calm: over an itame with flowing nagare, ji-nie, chikei and a nie-utsuri standing strongly on the ji, he sets a gunome mixed with choji and ko-notare, and in the upper half tobiyaki with a yubashiri-like feeling intermingle until the whole becomes a hitatsura that undulates flamboyantly. The published commentary calls it 「来派の作としては異色な出来口」[[c:4]] (an idiom unusual for a Rai work), the activity within the temper abundant and the nie-utsuri strongly expressed, an outstanding example among this smith's work and 「資料的にも頗る貴重」[[c:5]] (extremely valuable as documentary material) for the breadth of expression possible within the Rai tradition. What separates Kuninaga from his Yamashiro source is exactly this: his is the Rai manner carried a step away from its origin, the jigane standing where Kunimitsu's is packed, the utsuri turned to nie, and the school's reserve held even where, once, it gives way to hitatsura.
For the collector Kuninaga is a scarce Nanbokucho name whose extant work, signed and attributed together, is exceedingly few. He has no National Treasures. His record runs instead through the Important Cultural Properties, a signed first-generation tachi in suguha preserved at Eirin-ji in Yamashiro and an attributed tachi held at Sakurayama Shrine, with two Tokubetsu Juyo blades and a long run of Juyo pieces carrying the rest. The denrai roll is a daimyo one, the Hisamatsu Matsudaira house, former lords of Matsuyama in Iyo, the Owari Tokugawa, and other Matsudaira lines among recorded owners. The published sources call one signed example 「同作中のみならず同名中の白眉」[[c:6]] (the finest not only among surviving works but among all smiths bearing this name). Most of his blades are held rather than traded, and a signed Nakajima Rai comes to light only seldom, so a privately held example is a notable thing for a collector to encounter, and a document of how the Rai line continued once it had left Kyoto.
