Nobufusa signed one in three characters, Nobufusa , with a fine chisel set toward the of an , and that blade, from the Ōmura family of , is one of the six designated works on which he is known. He is an early smith of the Fukuoka school of . The published sources count him 「後鳥羽院番鍛冶の一人」 (one of the of the Retired Emperor Go-Toba), and the registers place him about the Kenpō era (1213 to 1219). The also enters a Nobufusa under about Genryaku, but the published sources read the surviving signed blades as the Fukuoka hand, of the Ko- generation after Norimune. They also record the old view that the smith signing 延房 is the same as the one signing 信房, and follow the view, stronger today, that the two are separate men.
His recognized work is a slender of high with , the upper half inclining forward to a , an elegant shape the published sources read as characteristic of its age. Over it he tempers a calm -toned mixed with , and small . and enter well, the temper is -dominant with a little , and the is at times subdued. The says of this temper that it 「古様さや優雅なる味わいを湛え」 (holds an archaic and graceful savour). Of a nearly two-character it concludes from the and together that the blade 「古一文字派の刀工と鑑せられる」 (is to be judged the work of a smith of the Ko- lineage). The runs straight to a small round, on one ending in . Honma's inventory of the Imperial collection adds a comparison of its own: beside Norimune and Sukemune his manner 「小丁子を主調としてやや華やかなものがある」 (is based on and is somewhat more flamboyant).
The is an , well forged, at times mixing and packing into , with and , and an stands on five of his six designated works. On the it is a , and the published sources write that 「地斑映りの立った精妙なる地鉄は本工の鍛造の技の高さを示している」 (the exquisite with its standing shows the height of his forging). On the two Kujō-family blades and on the of Honma's inventory it stands as a , and on one it is only faint. The activity of the lies in the , the and the small rather than in large clusters. On the the published sources find the work within the especially rich, so that 「地刃に古一文字の古雅な美点がよく表示されている」 (the archaic virtues of Ko- are well shown in the and ).
Within the signed work the published sources draw a distinction. The body of it is the -toned , but the pair of , one from the Kujō family and one from the collection of Kazama Yōkichi, open into something fuller. On the first a is tempered at the and the whole runs as a with and entering well; the second is a mixed with . Honma held the two to be by one hand, and noted as a point of the pair that 「焼出しが区際にある」 (the sits at the ). The remaining face of the record is an whose signature survives as a . The published sources value it, with a Kōchū of Kyōhō 1 (1716), as 「遺例の少ない延房有銘の作」 (a signed Nobufusa, of which few examples survive). Honma, by contrast, called the in his inventory comparatively plain in workmanship though a sound, fine sword, and counted his surviving works comparatively many among the early Fukuoka smiths.
He stands at the threshold of the school, before the flamboyant of the mid- Fukuoka . His own marks are the slender high- , the -toned temper gathering small and , and the standing over a refined . Reliably signed works, the writes, are 「頗る少なく」 (exceedingly few): it names the at Hie Jinja, a formerly an Imperial possession and now in the Tokyo National Museum, and the Hayashibara , beside only a few others. On the it notes that the closely resembles that of the Kujō-family , which makes it 「資料的価値の高い一口」 (a blade of high documentary value), and it calls that 「同工屈指の作」 (among the foremost works by the smith).
Fujishiro grades him Jo-jo , and the Toko Taikan values his work at 2,500. Six designated works stand on record, all of them signed: one and two blades, three in the two tiers together, two prewar , and the recorded in Honma's inventory. He has no National Treasure. Provenance runs through the Kujō family, the Kishu Tokugawa, the Senge of Izumo and the collector Kazama Yōkichi, whom Honma called one of the leading collectors of the Showa era. The Ōmura of presented the inventory to the Emperor Meiji. Of recorded whereabouts, examples rest at Hie Jinja, the Tokyo National Museum and the Hayashibara Museum of Art. With so few signed pieces, and most of them held rather than traded, a signed Nobufusa comes to light only rarely, and a privately held example is a notable thing for a collector of early to encounter.