Aritoshi (有俊) is transmitted as a swordsmith of the school within the Yamato tradition. The lineage encompasses two generations: the first, who signed with a two-character and whose activity is established by an extant work dated Einin 6 (1298); and the second, who signed with the three-character inscription "Naga Aritoshi" (長有俊) -- understood as an abbreviation of "Chobei no Jo Aritoshi" -- and is traditionally placed around the Kenmu era (1334-1338). Signed works by both generations are "exceedingly rare," a point the emphasizes with remarkable consistency, and this scarcity lends each authenticated piece particular documentary value for the study of the school.
The hallmark of Aritoshi's workmanship is a temper in that -- "standing out even among works" -- conspicuously incorporates , uchi-noke, and , "displaying an individualistic manner." The is typically a tightly forged or with flowing grain and a tendency toward , particularly near the cutting edge; the is characteristically wide and the stands high, features that strongly express the Yamato character. Very fine blankets the surface thickly, with fine appearing throughout, and the steel is consistently described as -- bright and clear. Along the , appears frequently, and emerges "in dotted succession" in the upper portion of the blade. The is straight, commonly finishing with vigorous and tending toward . Within the broader manner, Aritoshi is distinguished by a forging that is "comparatively tight with little tendency" relative to other Yamato attributions, and by of particular brilliance.
The reserves its strongest praise for the luminous quality of Aritoshi's : "the shining, beautiful adheres well, and the is bright and clear." This interplay of thick , vigorous , and within a fundamentally restrained produces blades that the examiners characterize as possessing "a deeply flavored and engaging style" beneath an overall "subdued () impression." His work embodies the Yamato aesthetic at its most refined -- dignified, contemplative, and rich in internal activity -- while the distinctive serves as the primary attribution criterion that sets his oeuvre apart within the lineage. The consistently affirms that among unsigned Yamato blades displaying these combined features, "judging it to be Aritoshi is the most appropriate conclusion."