Tadakuni is the first-generation smith who signed Harima Daijō, and later Harima no Kami, Fujiwara Tadakuni. His earliest name was Hironori; in 'ei 11 (1634), at the age of thirty-seven, he received the title Harima Daijō and changed his name to Tadakuni, the earliest title-bearing work on record being dated 'ei 13. He was a pupil of the first-generation , the founder of the school, and the son of Sōemon Yoshiie of the Hashimoto family; since he shared the founder's Hashimoto surname, the published sources judge him likely of the lineage, and note that he received his title considerably earlier than the second-generation Ōmi Daijō Tadahiro of the main house. He was retained by the Ogi domain, one of the three Nabeshima branch houses of Saga, and was active as an Ogi-domain smith. In old age he took the tonsure under the name Kyūtetsu, and his work extends into the Tenna era.
The published sources read his hand in two manners and call him highly skilled in both, but they place his true strength in the flamboyant . His is a gunome-chōji and , the temper often broad, the clove heads at times round, mixing in , angular elements and -like forms with scattered . Long enter frequently, with , the deep and well adhering. Above all it is the that names him. The sources say of one blade that runs vigorously through the , and that among his school he is the one in whom it is most conspicuous: 「刃中に砂流しがさかんにかかり」, 「一派の中でも最もそれが目立つ」. With it run , and the is bright and clear. The other recurring note of his clove work is the reach of its : in , the published record holds, his distinctive feature is a with long , 「足長丁子に特色がある」.
The beneath both his manners is the tightly forged with , the steel the school is known for. On his finest pieces it becomes the dust-fine laid thickly with entering, the bright and clear, and several blades carry the slight toward the edge that the sources note in his late work. Over that his second face is the calm one. He tempers a , at times a broad , deep in , and entering well, with fine and and at the a -like effect. The published sources record him plainly as skilled in both registers, 「直刃、乱刃ともに上手」, and on one late they observe that, against his usual habit, here the is not especially prominent, 「さまで砂流しが目立たず」, the whole finished in a quiet, restrained that shows this comparatively small body of straight-temper work. The in both manners runs straight to a , frequently with .
His record divides less by period than by manner, though the dated pieces let the late years be read. The Harima Daijō signature carries the body of his work; the Harima no Kami signature, used after his promotion and running through the , Enpō and into the Tenna years, marks the later blades. One Enpō 2 (1674) takes as its principal tone a varied large - mixed with -like elements and , deep in and , which the sources call a manner brimming with vigorous spirit. On his most ambitious clove work the temper widens a further degree into an ō-chōji-midare with and even slight , so high-tempered, the published commentary remarks, as to be rare among his blades, and they ask whether the first-generation Tadakuni was here aiming at the old : 「古作の一文字あたりを狙ったものであろうか」. The record places the difficulty of his oeuvre squarely on the table. Because the second generation was likewise appointed Harima no Kami, the first and second are hard to tell apart, and the sources note a view that much now called second-generation work may in fact be the first's.
What sets Tadakuni apart within his own school is exactly what the judges name. His and his bright are the shared inheritance, the komenuka-fine and the clear temper that every -line smith owes to the founder. His own signature is laid over that inheritance: the long- and, within it, the that runs more conspicuously in his than in any other hand of the school. On one the published sources read the workmanship as at first glance recalling Naoe , 「一見直江志津などの風を見せて上手である」, the Yamato-tinged streaming temper a measure of how far his reaches from the calm standard. He stands as the school's most accomplished maker of the flamboyant clove temper, the branch hand who carried the into a brighter, more active than the main line pursued.
For the collector he is a signed and well-documented name whose work survives entirely at the level. Fujishiro grades him Jō . He has no National Treasures and no Important Cultural Properties; his record runs instead through the ranks, where his appear across many sessions and the published sources repeatedly call them representative or typical examples by this smith, both and clear and bright. One they single out as 「傑出の一口であり、典型作でもある」, an outstanding and typical piece of his work. Several carry Yamano Ka'emon cutting-test inscriptions in gold inlay, documents of the edge as well as the hand, and a number bear chrysanthemum and crab-peony crests on the tang. The thirty-some designated blades on record are held in private and long-kept collections, their owners largely unrecorded, so a signed Harima Daijō or Harima no Kami Tadakuni is not beyond reach in the way a National Treasure is; it comes to the serious collector from time to time, with patience, and a fully realized flamboyant example, in which his runs at its most vigorous, is a thing to be sought out when it appears.