A small , signed Kunihiro and dated Shōhei 12 (1357), is the fixed point of his record: from it the published sources read the span of his activity, for signed work by his hand is otherwise scarce. Kunihiro worked in the school, the line of the period, and is transmitted as a son of Yoshihiro or, by another account, of Sadayuki. The published sources place him among the leading hands carried on from Ō-, in a school that, as they put it, emerged in the early and cast off the older traditional Kyūshū manner to establish a style in which the steel and temper are 'bright and clear, refined in workmanship' (地刃が明るく冴えて垢抜けした作風). Within that school Yasuyoshi, Yukihiro, Yoshisada, Kunihiro, Hiroyuki, Hiroyasu and Sadayoshi all inherited the master's manner; Kunihiro is the one to whom the boldest, highest-tempered work was assigned.
His characteristic hand is a large-patterned irregular temper led by undulation. The published sources name two manners in his work and describe the first as 'a somewhat large-patterned with as the main theme' (のたれを主調としたやや大模様の乱れ刃), into which he sets , , and with a pointed tendency, the whole tempered high and flamboyant. The is deep and the attaches thickly and unevenly, with coarse gathering in places; fine and spill into the and run freely, and -like appears frequently. It is the showiest of the -group manners, and the reason it is his: the house, judging -group blades, tended to assign the name Kunihiro to those examples showing 'the most vigorously unsettled ' (最もさかんに乱れ).
The is the constant beneath both manners. It is a standing mixed with and a flowing grain, thick in with bold entering frequently, the steel carrying a somewhat blackish cast. This is the -derived of the school, open and active, not the bright tight and of ; where the forging tightens on his smaller signed pieces the grows fine and the steel brightens. Over it the of the prime work runs into , thrusts up and ends pointed, with vigorous and a long return, while the quieter pieces run straight to a small round. His second manner, named alongside the first, is a -toned temper mixed with , calmer and seen chiefly on the and the .
Most of his surviving record is not signed at all. The school's long were shortened in later centuries into , and the great majority of blades that carry his name today are , wide in body with little taper, shallow in and large in the , the grand high- shape. On these the published sources affirm the school from every point and judge the manner 'most fittingly compared to Kunihiro within the school' (同派の国弘に最も擬せられる), precisely because the tempering is high and large in scale, the variable, the internal activity abundant and the -like well marked. The signed dated Shōhei 12 anchors the chronology; one signed survives, published in the Kōzan , and is held to be of high documentary value for the study of the whole line.
What sets him apart is named within his own school rather than against another. The hands of the smiths are so closely matched that individual attribution is difficult, and the published commentary is candid about it: the attribution to Kunihiro rests on the boldness and scale of the workmanship, not on a single personal tell. He is distinguished from his schoolmates by carrying the most flamboyant, highest-tempered of the group, his bold and pointed, thrusting the marks the judges look to. The commentary is honest about his standing within the line, granting that his technique 'falls far short of Ō-' (技術は遠く大左に及ばず); yet on his best small work the refined, bright and are found to share 'a continuous affinity with Ō-' (一脈大左に相通ずるものがあって), the kinship that places him among the school's leading hands.
For the collector Kunihiro is a scarce name. Fujishiro grades him Jō-jō . He has no National Treasures; his record reaches the Important Cultural Property rank in two signed preserved at shrines, one at Kotohira-gū in Kagawa and one at Shinonome Jinja in Ehime, both heritage held in religious keeping. Beyond these, the documented blades run through the higher modern tiers, four at and the rest at , with roughly fifty designated works on record in all. Their provenance reaches into the houses, a once held by the Tokugawa shogunal family and a blade transmitted in the Hisamatsu Matsudaira house, with examples now in the Tokugawa Art Museum and the Iwate Prefectural Museum. Signed work is exceptionally rare and the dated a document in itself; of the shortened , only a small number fall in the and tiers, so a Kunihiro comes to a private collector only seldom, and a signed example rarer still, a tangible record of how the school carried its bright, bold manner into the height of the .