Kuninaga is the smith the published sources call Nakajima Rai, a pupil of Rai Kunitoshi who left Kyoto for Nakajima in Settsu and carried the Rai manner into the Nanbokucho period. The Meikan lists two generations of the name, the first about Gentoku at the close of Kamakura and the second about Shohei and Oan; only the three-character signature Rai Kuninaga is known, and almost no dated work survives. This entry holds the first generation together with the mumei Nakajima Rai attribution, and the judges are candid about how thin the line between the two generations is: of one signed tanto they write that its generation 「その代別についてはなお検討の余地がある」 (remains open to further examination).
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, with thick ji-nie, frequent chikei and a quiet nie-utsuri rather than the bright reflection of the Kyoto mainstream. Upon it he sets a broad or medium suguha into which ko-gunome and ko-choji enter, with ashi and yo, ko-nie well adhered, and kinsuji and sunagashi running through. The boshi goes straight to a small ko-maru, or sweeps with hakikake. Most of the mumei katana carry a plain bo-hi cut through in kaki-nagashi. On the best of them the judges single out the steel itself, 「温潤でねばり気の感ぜられる地がねは見事である」 (the jigane, warm and with a felt tenacity, is splendid).
The judges fix his kantei in one recurring sentence. His work 「様式的には来国光に似るが, 格調の面で聊か譲るところがある」 (resembles Rai Kunimitsu in style but yields a little in dignity), so a mumei blade that reads as Rai yet falls just short of Kunimitsu is given to Kuninaga. They also say plainly that this is a convention to be questioned. Of one o-suriage katana the commentary sets out the problem: 「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」 (it begins with the question of whether it is right to assign him suguha works of somewhat lesser technique), and for the present it follows tradition. When the evidence is strong they commit, as with a katana of Kenmu-period vigour for which 「来派の中でも国長に鑑するのが最も妥当と言える」 (within the Rai school, an attribution to Kuninaga is the most appropriate).
Signed work is rare, and the first generation's rarer still: 「殊に初代と鑑せられるものは稀れである」 (pieces judged first generation are especially rare). The judges separate the generations by the chisel. On a signed tanto of slightly wide body they note that, unlike the second generation's thicker and rounder strokes, the first-generation signature is 「二代のやや太鏨で丸味あるものとは異って, やや細鏨で角張るこころがある」 (cut in a somewhat fine chisel with an angular feeling), and conclude 「初代銘である」 (it is a first-generation signature). A katana preserved with an orikaeshi-mei and a small wakizashi are judged first generation by signature and manner. A first-generation tanto, they record, is slightly wide with a little sori, itame mixed with masame, a suguha-toned temper with ko-gunome and a tight nioiguchi, the boshi straight to a small round.
A small signed group sits uneasily in this frame and is kept here with that question attached. One tanto is wide and extended with a thin kasane, its ko-notare mixed with gunome over a standing itame, and the commentary observes that it is 「一見, 初代信国に近似した出来口を示している」 (at first glance close to the first-generation Nobukuni). Another tanto departs from the Rai tradition with a temper based on midare. A signed katana breaks its wide notare into tobiyaki and yubashiri, praised as 「来国光に迫る技術が明示された優品」 (a fine piece showing a technique approaching Rai Kunimitsu). The published sources describe the second generation's short blades in just these terms, yet for these pieces they stop short of naming a generation.
For the collector Kuninaga is a scarce name whose signed work is especially few. He has no National Treasures. Two tachi are Important Cultural Properties, one held at Sakurayama Shrine. His standing otherwise rests on 55 blades in the Tokubetsu Juyo and Juyo tiers, one of them a Tokubetsu Juyo katana, nearly all of them o-suriage mumei attributions. The provenance is distinguished. A small wakizashi judged first generation was, its scabbard records, 「十代将軍家治の指料であったことがわかる」 (the sidearm of the tenth shogun Ieharu), presented by the Owari house. A mumei katana appraised by Hon'ami Koyu was 「雲州松江藩主松平治郷(不昧)の遺愛の一口」 (a treasured blade of Matsudaira Harusato, Fumai, lord of Matsue). A tanto is recorded as 「西条松平家伝来」 (handed down in the Saijo Matsudaira house). The attributed katana come to market from time to time and reward a patient collector; a signed first-generation piece is a genuinely rare encounter.
