Ishiguro Masatsune (stone inscription: 石黒政常), born in Horeki 10 (1760), was the founding master of the Ishiguro school of metalworkers and one of the most celebrated (town-carving) artists of the late period. He first apprenticed under Kato Naotsune of the Yanagawa branch, and subsequently studied with Yanagawa Naomasa himself, both part of the broader Yokoya lineage. Upon establishing independence, Masatsune combined one character from each teacher's name — masa (政) from Naomasa and tsune (常) from Naotsune — to form his professional name. He used the art names Togakushi (東嶽子, later written 東岳子) and, after passing the age of sixty, signed works as "Ishiguro-sai Jumyo Masatsune." His school attracted many gifted pupils, including Masayoshi, Masaaki, Koretsune, Masahide, and Masahiro, and the Ishiguro lineage continued to flourish through successive generations into the Meiji period. He died in Bunsei 11 (1828) at the age of sixty-nine.
Masatsune's technical command encompassed the full repertoire of the metalworker. His favored ground was finished with an impeccably regular , praised in designation records for its orderly precision. Upon this deep-black surface he executed designs primarily in (high relief) enriched with (polychrome inlay), deploying a remarkable palette of colored metals — gold, silver, , (scarlet copper), , and hi-irodo — to achieve effects of brilliant yet controlled chromatic richness. His demonstrate equal mastery of (sculptural carving) and nikubori (fleshed relief) on solid gold grounds, often employing (applied metal) and (applied inlay). A pair of dragon reveals his command of the dashi-keshi method and precise sankaku- (triangular chisel) work adapted from the Goto iebori tradition. Whether rendering the minutely differentiated plumage of a raptor, the undulating force of ocean waves expressed through polished relief with gold and silver ro- (dew inlay), or the delicate color gradations in a pheasant's breast, Masatsune's chisel strokes are characterized by an honest, finely detailed manner and a clean final polish that imparts an air of dignified refinement.
Masatsune's artistic significance rests upon his transformation of the Yanagawa manner into a distinctly personal idiom centered on bird-and-flower subjects and birds of prey — themes that became the hallmarks of his school. His compositions make masterful use of open space, creating what the examiners repeatedly describe as a "clear and limpid spirit." Yet within this decorative brilliance there persists a martial vigor suited to warrior taste, a quality that distinguishes the first generation's work from the more purely ornamental output of later Ishiguro artists. His oeuvre spans , , , , , and complete soroe- sets, demonstrating equal facility across every format of sword fitting. As an artist who bridged the Yokoya lineage's classical discipline and the expressive naturalism of the Bunka-Bunsei cultural efflorescence, Masatsune stands among the foremost representative metalworkers of -period Japan.