Kuninaga is the smith the published sources call Nakajima , a pupil of Kunitoshi who left Yamashiro and settled at Nakajima in Settsu, carrying the manner forward into the period. The records two generations of the name, placing the first about the Gentoku era at the close of and the second about the Shohei and eras; only the three-character signature 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 Kunimitsu while falling slightly short of him, and it makes the Nakajima attribution itself a standing question of connoisseurship rather than a settled record. His , 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 . Over a well-forged he mixes and a flowing , the grain tending to stand a little, -tatsu, with thick and frequent bold . His is a faint or a quiet standing on this open, standing grain, the steel a step away from the closely packed of the Yamashiro mainstream. That standing 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 , one of them writes that the Nakajima has from old times been directed to 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」 (the matter begins with the question of whether it is right that works of somewhat inferior technique have been assigned to him). For the present, the commentary follows tradition.
Over that his temper stays calm. The characteristic line is a -toned or medium into which , and a shallow enter, with and , well adhered, and and running through, the now tight, now bright. The runs straight to a small , or sweeps with to a slightly pointed turnback. This restrained register, not the flamboyant of a hand, is the inheritance he carries; and the published sources note that the first generation in particular was proficient in , 「初代は直刃を得意」とした. It is the steel and this quiet edge, taken together, that the judges weigh against 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 , attributed to Nakajima , wide in body with a over the standing , the temper a broad or medium , often carved with a plain . The signed pieces, encountered only from time to time, are the work of the second generation in with , wide and slightly elongated with a thin , the three-character signature cut large below the . The published sources draw a distinction within his own work: the first generation was the hand, while in the second 「二代にはむしろ直刃の作は少なく」, more irregular tempering becoming common. The signed and keep a consistent carving habit, a on the and on the , each with a beneath, a devotional program that sets them apart from the grooved blades.
One piece stands outside every part of this account. A , signed by , breaks the calm: over an with flowing , , and a standing strongly on the , he sets a mixed with and , and in the upper half with a -like feeling intermingle until the whole becomes a that undulates flamboyantly. The published commentary calls it 「来派の作としては異色な出来口」 (an idiom unusual for a work), the activity within the temper abundant and the strongly expressed, an outstanding example among this smith's work and 「資料的にも頗る貴重」 (extremely valuable as documentary material) for the breadth of expression possible within the tradition. What separates Kuninaga from his Yamashiro source is exactly this: his is the manner carried a step away from its origin, the standing where Kunimitsu's is packed, the turned to , and the school's reserve held even where, once, it gives way to .
For the collector Kuninaga is a scarce 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 in preserved at Eirin- in Yamashiro and an attributed held at Sakurayama Shrine, with two blades and a long run of pieces carrying the rest. The roll is a 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」 (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 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 line continued once it had left Kyoto.