A family of swordsmiths
He learned as a child with his grandfather and his father, helping at the Setagaya forge. His younger brother, Shōji (1945–2023), was the third Yoshihara Kuniie (吉原國家); both received their licence in 1965 and were named mukansa in 1982. His son Yoshikazu (1967–2018), whom he trained himself, was the youngest mukansa in history and died at 51.
The Ise shrine
He has been chosen three times to forge the sacred tachi (御神宝太刀, goshinpō tachi) that the Ise shrine renews every twenty years.
Outside Japan
Since the seventies he has taught forging outside Japan: demonstration forges in Dallas, San Francisco and Seattle, and swords that the Metropolitan Museum of Art in New York and the Museum of Fine Arts in Boston offered to buy from him. With Leon and Hiroko Kapp he wrote four books in English: The Craft of the Japanese Sword (1987), Modern Japanese Swords and Swordsmiths (2002), The Art of the Japanese Sword (2012) and, with the polisher Takaiwa Setsuo, The Art of Japanese Sword Polishing (2013).
Pupils
The English Wikipedia counts nine apprentices, his son among them. Among them is Ōno Yoshimitsu, with him and with Kuniie from 1969 and licensed in 1975. Kubo Yoshihiro tells in the NBTHK magazine that Yoshindo was the first swordsmith he met and that he entered his forge in 1989; he recalls that the master imposed nothing and kept saying: “if you want to improve, give it your all; and if not, it makes no difference if you slack off”.
On television
Besides the 1987 documentary, he has appeared on 「情熱大陸」 (Jōnetsu Tairiku, MBS, 2017), 「美の壺」 (Bi no Tsubo, NHK, 2020) and 「プロフェッショナル 仕事の流儀」 (Purofesshonaru: Shigoto no Ryūgi, NHK, 2021), among other programmes.