Kagemasa, who styled himself Shinji Saburo, was a swordsmith of the school in Province active during the late period, with dated works spanning the Bunpo, Shochu, Karyaku, and Kenmu eras. Although his genealogy is not clearly established, the existence of collaborative made jointly with Kagemitsu — bearing inscriptions from the Shochu and Karyaku eras — demonstrates that Kagemasa stood in an extremely close relationship with Kagemitsu, and he is accordingly regarded as either a disciple within the Kagemitsu lineage or a close relative, with some references identifying him as Kagemitsu's younger brother. Few signed works by Kagemasa survive today, and while in terms of rank of workmanship he yields somewhat to Kagemitsu, stylistically his manner shows a closely similar mode of execution and is of high skill. A separate, earlier Kagemasa working in the tradition of the early period is also recorded in the , distinguished by a more archaic and different signature style.
Kagemasa's forging characteristically displays tightly packed — at times mixed with or showing a slight flowing tendency — upon which fine-particle adheres thickly, fine enters, and stands out vividly. His encompasses several distinct modes: works centered on angular intermixed with , , and small , often exhibiting a tendency overall; pieces in mixed with and ; and examples of blended with . Throughout, and are present, and the characteristically tends toward , with adhering and fine and running through the temper. His frequently enters in and turns back in , forming what the describes as a sansaku- recalling Kagemitsu. A distinguishing feature of Kagemasa's own hand, noted across multiple examinations, is a subtle tendency — a in the cutting edge — together with a somewhat greater variety of tempering elements and a stronger degree of variation within the than is found in Kagemitsu's work. In certain pieces the forging becomes somewhat , with standing grain visible, which the identifies as an occasional characteristic that separates his work from the more consistently refined surfaces of his master.
The consistently evaluates Kagemasa as a smith whose workmanship approaches the realm of Kagemitsu, producing blades in which both and are bright and strikingly clear. His finest works are described as representative superior pieces that rival Kagemitsu's own, with forging in which rises with clarity and a bright tone of steel. Works preserving with original inscriptions are regarded as being of exceptional value, both as rare signed examples of a smith whose authenticated pieces are scarce and as excellent source material for research on his working period and characteristic style. Multiple affirm that and survive in condition — sound and well-preserved — underscoring the enduring quality of his craft within the mainline tradition.