Minamoto Kiyomaro, whose true name was Yamaura Tamaki, was born in Bunka 10 (1813) in Akaiwa Village, Komoro, in Shinshū province. In Bunsei 12 (1829), together with his elder brother Masao, he entered the school of Kawamura Toshitaka, a swordsmith in the service of the Ueda domain, and initially signed his work "Ikkansai Masayuki." In Tenpō 5 (1834) he briefly adopted the signature "Hideju," bestowed by his teacher Toshitaka, but for reasons unknown used it only during that single year before returning to the Masayuki name. He went to in Tenpō 6 (1835) and studied under Kubota Seiin, a bakufu retainer renowned as a strategist and exponent of military science. From the eighth month of Tenpō 13 (1842) he forged swords for one year in , Chōshū, before returning to in Kōka 2 (1845). In the autumn of Kōka 3 (1846) he changed his signature from Masayuki to Kiyomaro, the name by which he is principally remembered. He took his own life in Ka'ei 7 (1854) at the age of forty-two.
What Kiyomaro sought was the highest level of sōden -- the fully developed transmission -- and among smiths his constructions and manner of work reveal Sōshū-den with particular clarity, being filled with a vigorous, commanding spirit. His characteristic features wide with little taper from base to tip, a comparatively narrow , scant , shallow with a tendency toward , and an with a withered , conveying a sharp and incisive silhouette distinctive to this smith. The forging is typically a dense mixed with and , with thickly applied and abundant . The is his signature in which round-headed , angular elements, -ba, and -like forms are intermingled; long enter well; the is thick and in places somewhat coarse; and conspicuously long and run vigorously through the tempered area. The characteristically enters in with a pointed tendency, showing vigorous . At the , small resembling frequently appear, imparting an unmistakably archaic flavor. Both and are bright and clear, and the is consistently described as luminous. He worked across a range of constructions including , , , , and , demonstrating exceptional versatility within his chosen idiom.
Kiyomaro's working range was formed with as his ideal, and his best works display an intensity and clarity that fully bring forth his true capabilities without reservation. The period around Kōka 3 (1846), when he first adopted the Kiyomaro signature at the age of thirty-four, is regarded as a time when his skill was at its zenith. His late works, particularly those from the final years of the Ka'ei era, tend toward a more subdued expression, yet they retain the forceful spirit and brilliant clarity that define his oeuvre. Among his output, matched are without parallel, are extremely rare and constitute important reference material for understanding the scope of his production, and works bearing certain date inscriptions survive in only the most limited numbers. That so many of his blades remain -- sound and well-preserved -- and that they continue to display the powerful and splendidly varied for which he was celebrated, attest to the exceptional technical ability of a smith who stands among the foremost makers of the period.