The Nakajima designation identifies swordmaking traditions established when Kuninaga, a disciple of the Kyōto master Kunitoshi, relocated to the Nakajima district of Settsu Province during the late period. This move represented both geographical expansion of school influence beyond the imperial capital and the deliberate transplantation of technically sophisticated Kyōto -based forging practices into a provincial setting. According to historical sword compendia, smiths using this designation are traditionally counted as two generations: the first active during the Gentoku era (1329–1331), and the second working through the middle decades of the fourteenth century, spanning the Shōhei and eras. Signed examples are exceedingly rare, and most attributions rest on stylistic analysis of unsigned blades greatly shortened from their original dimensions.
Nakajima workmanship faithfully perpetuates the core technical vocabulary of the main school while exhibiting slightly more restrained execution. The forging typically shows compact or mixed with and , frequently with a tendency toward standing grain; the surface is heavily laden with fine that forms in thick, crystalline masses, producing a bright, clear appearance. enter actively and repeatedly, and faint often appears along the side. The follows a characteristic broad -based pattern, into which are mixed , , and small elements; within this foundation, and enter abundantly, and the is uniformly described as bright and clear. Internal activities—, , , , , , and uchi-noke—appear frequently along the , creating rich variation within the temper line. The typically forms with , often showing vigorous activity. The overall impression is one of technically accomplished work in which the foundational serves as a vehicle for highly active crystalline formations and internal dynamics, closely resembling the style of Kunimitsu but yielding slightly in artistic rank.
Extant Nakajima blades almost invariably preserve the bold proportions characteristic of -period production: wide with little taper from base to tip, shallow or deep (often retaining or despite shortening), and extended or . Even when greatly shortened, these blades retain an imposing, martial presence that pairs well with the vigorous, -laden forging and temper. The technical consistency across designated examples—tight with thick , broad with active , and bright —establishes a coherent stylistic profile that clearly descends from Kyōto traditions while expressing a distinctive provincial character. The combination of robust construction, excellent preservation in surviving examples, and flavorful within both and renders Nakajima an important regional expression of late and swordmaking, preserving the technical sophistication of the capital school in a relocated context.