An bearing the vermilion 千代鶴国安 is preserved at Atsuta Jingu, the kind of dedicated great-sword in which the name of this smith survives most directly, for almost everything else on his designated record is a greatly shortened and left unsigned, handed down with the attribution to Kuniyasu. The published sources transmit Kuniyasu as a man born in Yamashiro Province and, by one tradition, a grandson of Kunisue, who later "moved to and became the founder of the Chiyozuru lineage"; the reference works place him around the and Sadaji years of the period, noting that "the sword reference works set his era around the era". His is a hand read as the tradition carried out of the Yamashiro capital and inflected by the province that received it, and at first glance a blade of his "can appear akin to works of the Yamashiro homeland, particularly those around Kunimitsu", yielding only slightly on close examination, so that, as the published record puts it, the received tradition "is judged acceptable".
The feature that marks him apart from that homeland is the . Where the Yamashiro smiths forge a tight, refined , Kuniyasu's is mixed with and, in places, , and it stands somewhat open, a tendency the published sources read as his provincial flavor. Over this standing the forms thickly, at times dust-fine, and the enter frequently, while the steel takes a slightly blackish tone and a whitish cast, the that recurs across his blades. The published commentary makes this the decisive point of appraisal: it is precisely because the grain stands and the steel turns whitish and dark that "here the appraisal to Kuniyasu is confirmed", the work judged not the homeland's but his.
The temper is a into which small mix, the base sometimes carrying an extremely shallow tendency. Along the the edge is restless beyond what the homeland shows: , and at times appear, and enter, thick adheres and in places flares into a coarser, especially brilliant , while fine and run through a bright . The ranges from a quiet with to a far more active turnback, on one blade the growing strong and breaking up along the and running to vigorous on the with a flame-like, impression. Of one the published sources write that these features "clearly express the characteristics of work of the period", the inheritance still legible beneath the provincial cast.
Within this one prime manner the blades fan out along a single axis, from the restrained to the flamboyant. At the quiet end stand pieces whose runs nearly straight, the activity confined to slight and a nuance along the edge. At the active end stands the -era of the 61st session, dated by the reference works to around the Sadaji era, in which "an especially brilliant, coarser " sparkles here and there within the bright and the turns to its flame-like form; of this blade the published sources observe that "a rusticity exceeding even the Yamashiro homeland is conspicuous even in the ", naming the very excess of activity as the mark of the provincial workshop. The surviving blades are and almost without exception, so that the recognition rests on this reading of and rather than on a signature, the lone exception being the dedicated .
The published sources set Kuniyasu in relation to his school by resemblance and slight distinction rather than by contrast. Upstream he stands within the Yamashiro line, near enough to Kunimitsu that a first impression can mistake the two; the gap is one of refinement, the homeland's and holding a degree of polish his yield. Downstream he is the founder, the smith from whom the Chiyozuru workshop of descends, and the very features that distinguish his blades from the capital, the standing grain, the blackish whitish-cast steel, the rustic edge and , are the provincial inflection that opens that local tradition. The bright activity and the brilliant coarse of his most active work set him apart on his own grounded terms, a hand turned rustic in the north.
Fujishiro records no rating for him and his designated output is modest: five works carried to , with no National Treasure, no Important Cultural Property and no among them, four of the five the that carry the Kuniyasu attribution and one the signed piece that belongs to a different hand. No early provenance is recorded for his blades. What survives in a public sanctuary is the held at Atsuta Jingu, a great-sword preserved as patrimony rather than as a thing that trades, and it is in that dedicated piece, not in the market, that his name is read most plainly. None of his designated work is locked away as inalienable cultural property, so the handful of sit in the tradeable tiers; even so, a blade securely appraised to the founder of the Chiyozuru line is encountered only rarely, and the collector who meets one meets a inheritance read through the steel of .