Yamamura Masanobu was a swordsmith of Echigo Province, belonging to the Yamamura family -- a powerful warrior house that held the area near Takada and took their name from the locality of Yamamura. According to widely held tradition, the Yamamura invited the second- or third-generation Nobukuni from Kyōto and studied his methods of sword manufacture. Works bearing this name span several generations from the Nanbokuchō period through the early Muromachi, and the meikan record multiple smiths of the same name.

In the jigane, Masanobu's work characteristically shows itame mixed with nagare-hada, with a tendency toward hada-dachi; thick ji-nie accumulates and chikei enter conspicuously. In hamon, the NBTHK has observed both a suguha manner bearing a Kyōto flavor and a notare-based temper mixed with small gunome and occasionally hako-gakari elements. In the latter mode, the nioiguchi is bright, thick nie adheres, and internal activities such as kinsuji and sunagashi appear -- features that "clearly express the characteristic manner of the Yamamura group, which drew upon the lineage of Nobukuni." Horimono including katanadōshi and koshi-hi with gomabashi are found on some examples.

The connection to Nobukuni is substantiated not merely by documentary tradition but by the workmanship itself: as the NBTHK has noted, "what most fully convinces one of the plausibility of this tradition is that the workmanship of these surviving pieces closely resembles that of Nobukuni." Signed works by Masanobu are extremely scarce, and those pieces assessed as Nanbokuchō-period production are considered to rank higher in both workmanship and presumed antiquity within the Yamamura school.