Nobuyoshi is the one famous name of the Ryūmon group, a branch of Yamato swordsmiths active from the late period into the . The published sources are nearly unanimous on his origins: "Nobuyoshi is traditionally said to have been a smith descending from the Senjuin line", and because he lived at Ryūmon-shō in Yoshino District, on the road that runs from Yoshino through to Uda, he was given the byname Ryūmon Nobuyoshi. The group is said to have included other smiths, with names such as Nagayoshi and Yoshiyuki appearing in the reference works, but only Nobuyoshi became well known, to the degree that, as one commentary puts it, "when one speaks of Ryūmon, it refers to Nobuyoshi". No dated blade by him survives; the swordbooks place him around the Shōō or Bunpō eras.
The hand that defines him is not one manner but two, and the draws the division on nearly every paper. One mode forges "a lively , or a -toned temper into which chōji-ashi enter", with standing in the and a character coming forward. The other is a that frays into , in which " does not stand and the Yamato color is strongly shown", quiet and austere in feeling. His finest signed , the wide-bodied piece once held by the Hori viscount and treasured by Inukai Bokudō, is the showy mode at its best: a wide with shallow , mixing , , and angular elements, and entering, the tightening with , and uchi-noke worked in, with and fine . The published sources call it "foremost among works by the hand".
The is the constant that carries both modes. It is a well-forged that flows and inclines to , with thick laid finely and entering frequently, the strengthening toward the edge on the most Yamato of his blades. Over that the is the variable: on the -leaning blades a clear , sometimes a soft ; on the Yamato blades none at all. The runs straight and finishes in , often , sometimes a with a short turnback, and across nearly the whole record the is bright and clear. Even in the lively mode the temper stays -based with and set into it rather than opening into a free , so the bright with and is the Yamato root that holds the two manners together.
His signature divides as his workmanship does. Two ways of cutting the right element of the character 延 are observed, a blocky form resembling an abbreviated 正 and a cursive sōsho form resembling 氏; the published sources record that later writers "call the former Masa-Nobuyoshi and the latter Uji-Nobuyoshi". The distinction is not merely calligraphic, for the sources note that blades with the former signature tend to a more tightly knit and those with the latter to a more standing grain, and one signed is read as a transitional piece between the two. Signed works are set with a large two-character and survive in only a small number, so a genuine in- Nobuyoshi is a precious thing to encounter.
What places him is exactly this position between two traditions. His bright and chōji-ashi set the -leaning mode apart from the plainer Senjuin and , while the subdued -with- keeps him within Yamato. The published sources observe that his smaller-signature blades have since old times been confused with Ko- work, and that confusion is itself the measure of where he stands. On the , which form the bulk of his record, the judges affirm the attribution from the high- construction, the flowing -inclined forging and the bright alone, calling one such blade a full expression of "the characteristic features and merits of Ryūmon Nobuyoshi in both and ."
For the collector he is a rare early Yamato name carried by a single great work. Fujishiro grades him Jō-jō . A signed transmitted as an imperial possession of Emperor Go-Mizunoo is a National Treasure, and the published sources say plainly that "the presence of this celebrated masterpiece has contributed greatly to the high reputation of Nobuyoshi"; two further signed are Important Cultural Properties, one of them preserved at Shitsukiyama Shrine in Yamaguchi. These are heritage held in shrine and institution and are not encountered on the market. His blades carry distinguished provenance recorded on their own papers, the Hori viscount and Inukai Tsuyoshi on the , the Date of Sendai and the Uesugi among the . Beyond the locked tier his record runs through one , the and the prewar Jūyō Bijutsuhin, some twenty-six blades in the and ranks all told, most held rather than traded. A signed example comes to light only seldom and a fine attribution from time to time, so a privately held Ryūmon Nobuyoshi is a notable thing for a collector, a document of how Yamato and met in one Yoshino hand.