The Yokoya school was the largest metalworking lineage of the period, founded in the early seventeenth century when the first-generation Yokoya Soyo -- sometimes distinguished as "Sofu Soyo" or "Ko-Soyo" -- studied under Goto Injo Mitsutomi and established an independent atelier in . The school's trajectory was decisively shaped by the third-generation master Somin (1670--1733), who trained in the hereditary iebori manner of the Goto house but, finding its convention-bound idiom unsatisfying, resigned his shogunal stipend and entered the sphere of independent work. There he "exercised his abilities to the fullest, achieved great success, and came to be called the founder of " -- the town-carver tradition that would fundamentally reshape the world of -period sword fittings. Somin cultivated a close friendship with the Kano-school-trained painter Hanabusa Iccho, from whom he received guidance regarding pictorial conceptions, and also studied with Kano Tan'yu, deepening his art through direct engagement with painters' designs. His adopted son and successor Soyo (1700--1734) faithfully continued the atelier's methods, while Soju (1651--1734), a disciple connected with both the first-generation Soyo and Somin, contributed rigorously unified that exemplify the school's commitment to integrated, thematic ensembles.
The Yokoya school's collective technical achievement divides broadly into two principal modes, both originated or perfected by Somin and transmitted through successive generations. The first is richly modeled with polychrome metal inlay () in gold, silver, and on grounds, where the carving displays an overwhelming abundance of modeled volume -- bold rises and falls in the flesh producing a forceful and crisply articulated manner that clearly reveals the school's Goto lineage and the thoroughness of its training. Soyo's works in this mode are described as possessing "both the capability and the dignity expected of Somin's successor," while Soju's on achieves a dignified and well-ordered atmosphere across complete, unified fitting suites. The second mode is , a single-edge chisel technique that Somin originated, in which pronounced modulation and decisive strokes alternate depth and shallowness at will, producing modulations of speed and emphasis that recall ink painting. Soyo inherited this specialty with excellent technique, deftly alternating chisels of varying widths to combine bold with delicate linework. Among the school's most distinctive inventions are the celebrated "Yokoya lions" -- shishi rendered with such immediacy that one experiences the illusion that the lion might spring forth from the itself -- and Somin's innovative vertically oriented tatezu compositions depicting lions, tigers, horses, and other subjects from unconventional angles.
The Yokoya school's enduring significance lies in its having opened a new artistic direction through freer, life-sketch-based realism that broke decisively with the formalized conventions of the Goto house while retaining that lineage's technical rigor. Somin's command of grounds in , polished surfaces, and techniques such as , , and yobori was comprehensive, and this breadth of technical vocabulary was transmitted intact to his successors. Soju's hereditary mounting of the Uesugi family of Yonezawa Domain exemplifies the school's integrative vision -- every component sustaining a single coherent theme across the entire suite -- while Soyo's works, described as "extremely rare," lend special value to surviving matched sets. Whether working in the restrained monochrome palette of polished or introducing touches of color through kinhira- accents and gold , the Yokoya masters consistently achieved what the characterizes as a severity and awe-inspiring intensity that exerted a major influence on later generations of metalworkers, establishing the tradition as the dominant creative current of -period sword fittings.