The Ishido school (江戸石堂) is the capital branch of the Ishido lineage, a body of -era smiths who carried the tradition into and there pursued a single deliberate project: the revival, in the brighter steel of the early- forges, of the flamboyant worked by the medieval Fukuoka- masters of . The school's makers came up from Omi by way of Kyoto rather than directly, the Akasaka-signed blades of Mitsuhira fixing that route, and several of its leading hands trace to the Kyo-Ishido line before the move to the capital; Heki Mitsuhira, eldest son of Yamashiro-no-kami Ippo, and Tsushima-no-kami Tsunemitsu stand as the twin pillars of the early school, while the Ishido Korekazu line carried the house specialty forward, the seventh-generation Korekazu keeping it alive through the nineteenth-century revival. A separate strand runs through Yamato-no-kami Yasusada, whom recent research and the Bengi place within the Kishu Ishido group, a -era master of the capital whose temper turns toward the angular rather than the of his school-fellows.
What binds the school is a shared vocabulary rather than a single hand. The defining work is the tempered over a bright , a crowded line mixing , , round-topped and small with angular and pointed elements, the rising and falling in marked height, the and entering vigorously, the clear; on the most successful pieces a stands in the , the - reflection raised again on a blade, the single feature that carries the comparison furthest. Mitsuhira tempers this revival chiefly in , and the reads his over its as the fullest realization of the school's program, a splendid that recalls the old . Korekazu departs precisely here: where the other -leaning smiths held their in , he forged the house pattern in , deep in and thick in over a approaching a - tightness, with , and threading the edge, a pattern carried on a -leaning base. Yasusada marks the school's outer divergence, working a mixed with that boxes at peak and valley, the inclining to a subdued and a steeply raised among his marks, his -leaning temper inherited through Kaneshige. Across all of them the is the constant that underwrites the edge, a densely forged , sometimes mixed with , the laid dust-fine and entering well.
To an Ishido blade is to read a revived set on an unmistakably : the draws the eye to old , but the steel beneath is the bright, clean forging of the and later forges, frequently on the broad body, thick and contracted of the era, with Mitsuhira's transitional silhouette retaining a touch of and standing . The when present confirms the school's intent; the choice of over separates Korekazu from his fellows; the boxed and mark out Yasusada, whose hand is read against Kotetsu rather than against his school. The ranks the best of these makers among the leading smiths of their respective ages, Mitsuhira as one of the most skilled to represent the Ishido and Korekazu beside Jirotaro Naokatsu and Hosokawa Masayoshi among the late- masters. Provenance is generally quiet, held in private and public hands rather than great houses, though the school's blades carry the texture of their moment: the Yamano gold-inlaid cutting-test inscriptions recur on Yasusada and on Mitsuhira's earliest dated work, one Korekazu blade is held by the Imperial Family, and his man'yogana and joi-slogan inscriptions voice the late- current that the school's final flowering of - outlived.