Kunishige worked within the Mizuta school of Province, a lineage that flourished from the late period into the era. The most celebrated smith of this name is Otsuki Yogoro Kunishige, commonly abbreviated as "Daiyogo," who was the son of Otsuki Saburobei Kunishige and is recognized as the foremost master of the Mizuta school. The observes that "the nationwide prosperity of this school during the period was likely due to the presence of such superior craftsmen." Earlier work signed "Ko-Mizuta Kunishige" is dated to the late period, with a bearing the date Tensho 20 (1592) among the few signed examples by the older lineage.
The Ko-Mizuta works display a of dense with and , and a built around as the principal theme, incorporating small and in what the describes as an "overall somewhat busy" manner, with a tightly formed and attached as the chief point of appreciation. The later Daiyogo Kunishige, by contrast, excelled particularly in the , producing with prominent standing grain, well-adhering , and , tempered in bold -style that in the upper half becomes nearly , with deep and coarse . The on such works enters in irregular with , burning down long to the . The tang tip in the Mizuta manner is characteristically .
Signed examples by both the Ko-Mizuta and Daiyogo lines are described as "comparatively few," lending particular significance to surviving blades. The Ko-Mizuta of Tensho 20 is called "not only a typical example, but also one of his representative works," while the Daiyogo Kunishige is praised as "a superior craftsman who exceeded his father's skill." This rarity of signed work is traditionally attributed to signatures being removed or blades being shortened and reworked into superior pieces -- a testament to the enduring regard in which Mizuta workmanship has been held.