A small designated in 2003 fixes Kunimitsu in time. On the of its tang the date Koan 11 (1288) is cut with a rather thick chisel, on the the fifth month, first day, and beneath it the two-character name Kunimitsu. The published sources identify him as the son of Norikuni and the younger brother of Kuniyoshi, a smith of the school of Yamashiro in the late period. Secure examples of his work are exceedingly rare. Beyond this they know only a few, among them two designated Important Cultural Properties and a whose inscription includes the title Saemon no Jo. Of the dated blade they write that its and fully display the virtues of work, and that "above all, the documentary value of the Koan 11 date is beyond measure". Because the name is cut on the , they add, the may have been made as a , worn at the right side.
The published sources describe his manner in a few consistent words. On an designated in 1970 they write that he "signed in two characters, Kunimitsu, his fine, excelling at and highly skilled". On a designated in 2019 they put it more fully: his work is marked by a that is "tightly forged, with attaching in fine particles, beautiful, and he excelled at a calm ".
The is , tightly forged, with fine and . On the 2019 the attaches in fine particles, enter well and a faint rises. On the dated the is mixed with flowing grain and , the attaches well with fine , and the colour of the steel is called exceptionally bright and clear. The 1970 is forged in an that flows overall, with attaching well.
The temper is a . On the 2019 a few enter, attaches well, appear in places in the upper half, a slight -like effect runs on the and enter here and there, the bright and clear. The 1970 mixes and into its , the tending to tightness, with and some slightly coarse and . On the the undulates shallowly, mixed on the with small , the deep and the thick. The runs straight to a on all three, turning back rather short on the 2019 and somewhat long on the .
The shapes vary with the form. The 2019 is of standard width, tapering clearly, with a shallow and a , and carved kaki-nagashi on both faces. The 1970 , and shallow in curvature, has a compact inclining to . The is slender, thin and small, with , and keeps traces of a on the and of what are taken for goma-bashi on the . Its two-character signature, the published sources note, shares points with that of the Important Cultural Property . Of the 2019 , whose tang carries a red-lacquer attribution, they single out the well-refined and call the blade, with its gentle form and bright, orderly , "an excellent example of this smith's attribution, possessed of a dignified and elevated character".
Five designated works on record carry his name. Two are Important Cultural Properties, both signed Kunimitsu, with a , forged in and tempered in : a of 73.3 cm at Yoroji in Gifu, which the published sources name as his best-known representative work, and a of 80.3 cm at the Kurokawa Institute of Ancient Cultures in Hyogo. They are heritage held by a temple and a research institute. The other three are blades: the dated and the two . He has no National Treasures. Fujishiro ranks him Jo-jo . A blade by Kunimitsu reaches the market only rarely, and a signed one, given how few survive, is among the scarcest things a collector of work could encounter.