Kuninobu is named in the published sources as one of the leading disciples of Taro Kunimura and a representative smith of the school of , his active period traditionally placed around the Karyaku era at the close of the period. The same sources are candid that his surviving works are "extremely few" beside those of fellow members such as Kunitoki, Kunisuke, Kuniyasu and Kuniyoshi, so he is known through a small group of signed and a handful of shortened blades attributed to him on appraisal. The line is Yamashiro by descent. Its founder Kunimura is transmitted in the prevailing account as a grandson in the female line of Kuniyuki; a fuller version makes him the child of Hiromura of the Yamato Senjuin school, who married a daughter of Kuniyuki, while one early text places Kunimura in the gate of Kunitoshi. The school flourished at Kumafu in Kikuchi District from the end of into the period.
From that root the make stands close to , and the published sources list the points by which it nonetheless departs from as the school's chief attractions. In their words, "in the forging a tendency stands out and a whitish appears"; the is somewhat subdued, the activity within the edge is calmer, and the is fuller in its roundness with a shallow return. Kuninobu carries all of these. They add a point of their own about the line as a whole: smiths show few sharply individual mannerisms, and "compared with there is a tendency for the and to be somewhat weaker".
His is an mixed with and flowing that tends to stand rather than lie flat. Fine gathers densely over it, fine enter, and collects in patches. Over this rises a whitish , recorded on nearly every blade of his, the faintly whitish cast the sources call common to Kyushu work. On the best-forged pieces the knits into a of notable refinement, and one is singled out for the excellence of its forging together with a bright .
The temper is throughout. It runs broad on the shortened and mostly middling or narrow on the slender signed , leaning into a shallow with and a touch of in the lower half. and enter, and the is tight, with , and inclined to sink. His most celebrated feature is the , a second line running along the edge. The sources write that "the way runs along the edge is a great point of appreciation for this school", and on his blades it shows more clearly and runs longer than usual, at times built from -like dotting the . and appear in the upper half. The turns back in a full with a shallow or finishes in , with at the tip.
His single manner divides by register rather than by period. The signed pieces are slender of high with and a compact , or only slightly shortened, the two-character cut large with a slender chisel above the toward the . On them and enter the at intervals, which the sources call "a feature not uncommonly seen among smiths of this group". The signature itself is a means of attribution. The ear-shaped right half inside the -gamae is common to the school, but Kuninobu cuts the vertical stroke within it at a marked diagonal and on one sets slightly to the left of . On a shortened where only the character survives, the held the maker to be certain from that handwriting alone. The second register is the , wide and thick, with deep and a slightly extended , a bearing the sources liken to "the silhouette of Kunimitsu of the homeland tradition". These are given to him over his fellows because their work is "more refined than the work usually seen", and the sources tie the best of them to his signed designated an Important Cultural Property.
That , held by the Mitsui Bunko in Tokyo, is now among the works on record under his name. Its Important Cultural Property listing records it with a and a broad mixed with , and dates it to the period, while the places his activity in late ; several of the texts accordingly date his blades late to . Eight designated works stand on record: that Important Cultural Property, two blades of rank and five of . The passed through the Satake house of Akita and was later treasured by Miyoji, and the sources call it a masterpiece among Kuninobu attributions, a blade in which "a high sense of dignity is felt". An early is said to have once carried a Kochu naming it Kunimitsu. The Important Cultural Property is preserved as heritage and will not change hands. Of the and blades, the signed are valued precisely because so few survive, and an example by Kuninobu is among the rarer encounters in the field, met with patience rather than sought at will.