Omi Daijo Tadahiro was the legitimate heir of the first-generation , founder of the main line. When his father died in 'ei 9 (1632), Tadahiro was still a youth of nineteen; nevertheless, works by him are already seen from that year. This was due not only to his innate aptitude and technical ability but also to the considerable support of the disciples active under the first generation, who cooperated in sustaining the workshop. He received the court title Omi Daijo in 'ei 18 (1641) and died at the age of eighty-one in Genroku 6 (1693). Over a career extending more than sixty years, he left behind the greatest number of extant works among all smiths. His father, originally known as Hashimoto Shinzaburo, had studied under Myoju in Kyoto before returning to the castle town of Saga under Nabeshima domain patronage; one rare early by the first-generation Tadahiro bears a supplementary inscription by Myoju that substantiates the master-student relationship and is prized as documentary material.
Tadahiro's workmanship divides broadly into two modes: and . In his , the forging presents a tightly packed with extremely fine adhering thickly to produce the distinctive (rice-bran-like) texture for which work is celebrated. The is characteristically deep and band-like, with thick , and the steel is bright and clear. Fine and appear throughout, and the runs straight into . In his mode, long enter frequently with intermingled, the are relatively aligned, and in places the temper becomes juka-like (layered-flower). Collaborative works with his son, the third-generation Mutsu no Kami , survive in comparatively large numbers; among these, the and occasionally present a paired contrast in the so-called kotekashiwa arrangement. Rare examples include a modeled after Hiromitsu, and pieces bearing the added inscription -tan ("made of true, well-refined steel"), which often show especially fine workmanship.
The consistently praises Tadahiro's production as displaying "bright and clear and " with a that is "deep, band-like, and ." His finest pieces are described as "powerful in both and " and "filled with overflowing martial vigor," while even his standard output is commended for its (sound and well-preserved) condition and "meticulous fineness distinctive to work." Among the second generation's output, works of greater length and wider are singled out as "bold and imposing" and "overwhelming the viewer." Whether in the deep-, thick- that constitutes his greatest specialty, or in the flamboyant with its dense, long-legged clove forms, Tadahiro's mastery across both registers places him at the summit of the school and among the most accomplished smiths of the period.