Kuniyuki is regarded as the de facto founder of the school of Yamashiro Province, the lineage that achieved the greatest prosperity among the Yamashiro groups from the mid- period through the era. Transmission records cite a smith named Kuniyoshi as the school's progenitor, but since no extant works can be securely attributed to Kuniyoshi, and because the characteristic style of the school "was devised and established by Kuniyuki," he is universally treated as the founding figure. Kuniyuki is also known as " Taro," said to have been Kuniyoshi's son. None of his blades bear a production date; however, because a by the two-character Kunitoshi — traditionally regarded as his son — is inscribed Koan 1 (1278), the commonly accepted dating of Kuniyuki to around the Kogen era (1256-1257), or more broadly the Shogen and Bun'o eras (1259-1262), is considered reasonable. Signed works in form are comparatively numerous, while among only a single unquestionably authentic example is known; likewise, reliable surviving short blades such as the Shimazu-transmitted are exceedingly scarce.
Kuniyuki's present various types of : slender, orthodox forms with showing a gentle "yin" construction, and works of ample with a bold, powerful "yang" bearing and -style , yet in all cases it is customary for the to take on that distinctive boar-neck form. The forge is characteristically a tightly worked , densely covered with extremely fine and enlivened by , producing steel that is strong, clear, and often described as moist (shitsujun). frequently stands out, at times taking on a aspect. The is broadly -toned, mixing , , and angular elements with deep and thickly adhering ; and enter abundantly, while and run through the temper. Small and at the sometimes produce a "pheasant-thigh" () configuration, and is frequently encountered. The is customarily tempered in with . His texture differs from the finely grained refinement of later masters such as Kunitoshi and Kunimitsu; Kuniyuki's works often show a tendency toward , a feature shared with two-character Kunitoshi.
Across the evaluations, Kuniyuki's blades are praised for manifesting an archaic manner (koyo) and a "weighty style with great presence" that connects directly to the mid- period character. The adjective — sound and well-preserved — recurs with remarkable consistency, underscoring the physical integrity that his surviving works have maintained. Examiners describe the balance and condition of in the and as demonstrating "a notably refined, sophisticated workmanship" and a "high technical level." Whether bearing an original with signature or authenticated through appraisals by Kochu, Kuniyuki's blades are recognized as works that "fully manifest this smith's key attractions." The rare with its predominantly is noted as "valuable material for understanding Kuniyuki's workmanship," anticipating the -ba later developed by Kunimitsu and Kunitsugu. His oeuvre thus stands as the wellspring from which the entire school tradition flowed — a body of work combining archaic elegance, vigorous activity, and a dignified bearing that established the aesthetic vocabulary his successors would refine across the following century.