A dated the fifth month of Shōhei 5 (1350) anchors the career of Nagamori of . Of his Shōhei-dated work the published sources write that it "raises the previous upper limit of his dates, and is valuable material for the study of Nagamori". Nagamori has been transmitted since old times as a son or pupil of Chōgi (Nagayoshi). His dated blades run from Shōhei 5 (1350) and Shōhei 8 (1353) through Shōhei 22 (1367) and the Kentoku years, to the lately surfaced Eiwa 4 (1378) and Kōō 1 (1389). They place him in almost the same years as Chōgi rather than a generation behind, and like his teacher he signed overwhelmingly with Southern Court era names. A Chōgi dated Jōwa 6, the equivalent of Shōhei 5, is Chōgi's earliest dated piece, so the two stand together at the head of the dated record. One goes further, noting that he "may even be seen as slightly earlier than Chōgi".
His hand is work carried into the manner of the Chōgi line. The temper is a whose waists open in the Chōgi manner, mixed with , and angular, pointed elements, wide and varied in its line. and enter, adheres, and fine and are mixed through it. and run in the , and the is bright and clear. The published sources grant the affinity with Chōgi in the opened waists and the variety of the temper, and then settle the attribution on one distinction: his resolves into somewhat smaller patterning than the teacher's. Of one blade they write that "in the way the becomes somewhat smaller in pattern, the attribution to Nagamori is convincing". They read this as a manner falling a little short of Chōgi and Kanenaga in vigour and technique.
He forges an mixed with , the standing a little and flowing in places, with laid on thickly in fine particles and entering well. The published sources name the strong of and as the character of the Chōgi line, and it gives his its depth. A stands over it, often only faintly, and the published commentary notes that among blades of this type "there are some on which no appears at all". The runs in and turns back in a , at times rising to a pointed tip with ; on the signed pieces it runs up and turns back long. is carved through on most of the shortened , and the signed carry su- and .
His record falls into two groups. The first is a small body of signed and dated work, mostly and short or , with a long signature on the and a date on the . Its peak is the Shōhei 16 in the , a wide, elongated tempered in a large with deep and abundant , which the judges read as showing the . They call it "one of the foremost among Nagamori's works". A Shōhei 21 recorded in Honma's inventory of the Imperial collection belongs to the same group. Its entry observes that his signature is close to the work of the period and differs from Chōgi's, and that "surviving works are very few, and await further study". The second and far larger group is the , wide in body with an extended or large in the shape, attributed to him by the smaller-patterned reading of the Chōgi style. The published sources stress that beside the opened he leaves a varied small , shallow and even -toned work, and they call him "a smith of comparatively broad range". That breadth, with so few signatures to set against it, is why the attributions turn on so fine a point.
Within he belongs to the Chōgi group, beside Kanenaga and the other hands of the school, and the comparison the judges draw most often is with Chōgi himself. His and the brightness of and keep him a smith. The thick , abundant , and place him within the manner of the Chōgi line, while the smaller scale of his and a slightly gentler force separate him from the master. One blade is praised for a bold and splendid air, its varied and showy and rich in activity, an excellent work convincingly attributed to him.
Fujishiro grades Nagamori Jō . He has no National Treasure and no Important Cultural Property. His record runs through one and thirty-nine blades, forty across the two tiers, with the Shōhei 21 recorded in Honma's inventory of the Imperial collection, forty-one works on record in all. Of recorded whereabouts, two are held by the Tokyo and Kyoto National Museums. A of rank carries a silver-inlaid ownership inscription of Fukushima Kamon-no- and an incised note by Tagaya Eishi, who wrote that he bought it with his stipend, wore it always, and bade his descendants keep it. Because authenticated signatures are extremely rare, the dated pieces are valued as evidence as much as objects. A signed Nagamori comes to market only seldom. The attributed to him appear more readily, Chōgi-line blades of bright steel and varied temper within the reach of a patient collector, and a documented signed example is a notable thing to encounter.