Shodai Tadahiro was the same individual as shodai Tadayoshi, known by the common name Hashimoto Shinzaemon. He served as a retained smith of the Nabeshima domain of Hizen Province. In Keicho 1 (1596), by order of the domain, he entered the school of Umetada Myoju and learned sword-forging technique. In Keicho 3 (1598) he returned to his province, took up residence in the castle town of Saga, and under the domain's patronage prospered greatly. In Genna 10 (1624) he went up to Kyoto once again, received the honorary title Musashi Daijo, changed his name from Tadayoshi to Tadahiro, and at the same time changed his clan name from Minamoto to Fujiwara. He is said to have died on the fifteenth day of the eighth month of Kan'ei 9 (1632).

The hallmark of shodai Tadahiro's workmanship is the forging often described as komenuka-hada: a tightly packed ko-itame-hada on which extremely fine ji-nie adheres thickly, with chikei entering well. This characteristic jigane appears consistently across his oeuvre and constitutes one of the defining features of Hizen-school swords. Upon this foundation he most often hardened a wide suguha in which ko-ashi enter abundantly, mixed with yo; the nioi is deep, ko-nie adheres well, and kinsuji and sunagashi appear while the nioiguchi remains bright and clear. The habuchi shows hotsure, at times mixing vigorous nijuba and kuichigai-ba. Yet his range extended well beyond the typical Hizen idiom. Certain works depart from his usual manner entirely -- a tanto giving "the impression of viewing a Samonji" piece, executed with reduced niku at the fukura and only slight curvature; or a katana that "calls to mind an old Yamato work -- above all, something in the vein of Tegai Kanenaga," in which the boshi finishes yakizume with vigorous hakikake. Even in such utsushi, the komenuka-hada forging identifies the work unmistakably as Hizen. Of special note is a katakiriba-zukuri tanto -- a construction at which his master Myoju excelled -- tempered in ko-nie-deki with an urumi character, bearing carvings by Umetada Shichiza that Honma judged "the finest among tanto signed Musashi Daijo."

Shodai Tadahiro's works range from imposing katana of wide mihaba and deep sori to refined tanto of modest proportions, spanning his career from the Musashi Daijo signature period through his final years. The blade carried as the personal sash-worn sword of Nabeshima Kii-no-kami Naomoto, lord of the Ogi domain, testifies to the esteem in which his craft was held within the Nabeshima household that sustained his art.