Family and master
According to the Japanese Wikipedia, he was born in 1614 (Keichō 19), the son of the first Tadayoshi (忠吉, Tadayoshi), smith of the Nabeshima clan who from 1624 signed Musashi Daijō Tadahiro and died in 1632. The sources disagree on his place among the brothers: the Japanese Wikipedia and Saga Prefecture make him the youngest son; the Nihon jinmei daijiten (日本人名大辞典, Nihon jinmei daijiten), on Kotobank, the eldest. Nor do they agree on his civil name.
The Japanese Wikipedia adds, as tradition, that he trained with Kawachi Daijō Masahiro (河内大掾正広, Kawachi Daijō Masahiro), grandson and pupil of the first Tadayoshi.
The succession of 1632
According to Saga Prefecture, when his father died in 1632 (Kan'ei 9), at about 19, he inherited the forge and took the name Tadahiro. The Japanese Wikipedia stresses that he never signed Tadayoshi, although in the house it was usual to sign Tadahiro first and take Tadayoshi on inheriting, as the fifth and sixth generations did; it explains this, without evidence, by his being the son of a concubine.
Title
According to the record of the Kyūshū National Museum, he received the title of Ōmi Daijō in 1641 (Kan'ei 18). Before that he signed 肥前国住藤原輝広 (Hizen no kuni jū Fujiwara Teruhiro); afterwards, 肥前國住近江大掾藤原忠広 (Hizen no kuni jū Ōmi Daijō Fujiwara Tadahiro) on katana and 近江大掾藤原忠広 (Ōmi Daijō Fujiwara Tadahiro) on wakizashi. None of the other sources consulted gives that signature from before the title, with the name 輝広 (Teruhiro). The Japanese Wikipedia specifies the month of the title: the seventh.
His career
The NBTHK Sword Journal has him active from the age of 19 to 80 (no. 787, 2022), and considers him the shintō smith, and perhaps the smith of any period, who made the most swords (no. 726, 2017): there are blades dated in the Kan'ei, Shōhō, Keian, Jōō, Meireki, Manji, Kanbun, Enpō and Tenna eras, and about half are from Kan'ei. That is why his work covers almost every manner of the school.
For the Saga Prefectural Museum, which devoted an exhibition from its collection to him in the winter of 2025–2026, his long life allowed him to make many swords, lead the school and establish the prestige of Hizen swords. The house served the Nabeshima clan throughout the Edo period and produced more than a hundred smiths, according to Saga Prefecture.
His sons
According to the Japanese Wikipedia, his eldest son was the third master of the house, Mutsu no Kami Tadayoshi (陸奥守忠吉, Mutsu no Kami Tadayoshi), from 1637 to 1686; the second, Shinbei, made firearms, and the third was the first Tadayuki (忠行, Tadayuki), smith of the Ogi domain. This Tadayuki of Hizen is not Settsu no Kami Tadayuki, of Osaka.
His death
He died in 1693 (Genroku 6), aged 80, according to the Japanese Wikipedia, Kotobank and Saga Prefecture; the Japanese Wikipedia gives the 27th day of the fifth month, and Kotobank the 28th. The Metropolitan Museum of Art in New York gives his dates as 1614–1694. The graves of the house, from the second to the ninth generation, are at the Chōan-ji (長安寺, Chōan-ji) temple in Saga.