Tadahiro, called Heisakuro, was the legitimate son of the first-generation and the second head of the main line at Saga. He was nineteen when his father, by then no Daijo Tadahiro, died in Kan'ei 9 (1632). The published sources credit both his own talent and the disciples his father had trained, who carried the young head of the house, and his dated work survives from Kan'ei 10. On the twenty-second day of the seventh month of Kan'ei 18 (1641) he received the title Omi no Daijo, and he worked until his death at eighty-one in Genroku 6 (1693). That career of more than sixty years left, in the words of the published sources, more works than any other smith.
His work falls into two manners, and , and the published sources hold him highly accomplished in both, with his greatest specialty. It is a comparatively straight of deep with adhering thickly, at times tinged with a shallow and a little , and entering well, fine and running through it. In places the thickens into a band, and it stays bright and clear. The runs straight to a . The has the balanced curvature of work, and on some blades it is broad, long and heavy, with a touch of at the base.
The is the : a tightly forged with no looseness, laid dust-fine and thick, fine entering, the steel clear. On his best blades the published sources describe forging of unmatched quality and both and clear and brilliant. He was also the first smith to add the shinkitae , "made of truly forged steel", and the published sources observe that this begins with him among smiths. Blades bearing it are often of especially fine forging.
His work divides by period as well as by manner. Before the title he signed every blade no ju Fujiwara Tadahiro, the same form as his father's presentation signature, and the published sources separate the two hands by the strokes of 藤 and 廣. Many of these early blades are dated; after the title dated pieces become rare, so the Shoho, Keian and Enpo dates on record are prized. The early work is read as the vigor of youth, showing an unconstrained boldness beside his later production, and some of it comes close to his father's no Daijo work, which the published sources attribute to his father's collaborators still working beside him. His runs through both periods. In the published sources rank him above even the first generation: a wide temper of with , the heads comparatively even so that the cloves stand shoulder to shoulder, long entering thickly and gathering in the valleys. They call it the so-called long-legged . A dated the very day he received his title, its written in an archaic manner after work, is read as a commemorative piece. A small by him, carved probably by Yoshinaga, was aimed at old work such as Kunimitsu.
Within the main line his long career joins the founder to the later generations. He trained many pupils, and the published sources record that the third-generation and fourth-generation served as his substitute makers and signers. Joint works with his son Mutsu no Kami , each signing one side of the tang, survive in comparatively large numbers. On some of these the published sources judge the forging and temper to be largely the son's hand. His deep- over the became the measure by which later work is read.
Fujishiro ranks him Jo-jo . He has no National Treasures or Important Cultural Properties on record. His standing rests on 131 blades in the and tiers, three of them . The published sources call one of these work outstanding among his production, forceful and bold in both and . Recorded provenance runs through the Imperial Family and the Nabeshima house his line served. One was the personal sword of the domain lord Nabeshima Katsushige, and a blade survives in its Nabeshima family mounting for a woman of the house. Because he was so prolific, signed Omi no Daijo Tadahiro blades appear on the market with some regularity. A papered example is within reach of a patient collector. A blade, or one of the dated pre-title pieces, appears only from time to time.