Miyoshi Nagamichi (三善長道), also known as Miyoshi Toshiro, was in effect the founder of Aizu . Born in 'ei 10 (1633) in Aizu, he was the grandson of Nagakuni, a smith who had resided at Matsuyama in Iyo Province before relocating to Aizu in the service of Kato Yoshiaki. His father Masanaga likewise accompanied the family's transfer. Nagamichi initially signed as Michinaga; in Manji 2 (1659) he received the court title Mutsu Daijo and adopted the name Nagamichi. He died in Jokyo 2 (1685) at the age of fifty-three. One tradition holds that he studied under Tsuda Sukehiro, yet the consistently observes that "many works show a style close to that of the Nagasone group."
His characteristic features mixed with , forming an undulating -ba with pronounced height variation that "closely resembles the manner of Nagasone Kotetsu's so-called '' period." In places, two gunome run together to produce a distinctive gourd-shaped (hyotan-ba) effect, a hallmark of his finest work. The is typically mixed with and flowing grain, with fine thickly adhering and delicate entering well. The is deep, adheres thickly, and and appear in the hardened area, yielding a "conspicuously active workmanship." His likewise recalls Kotetsu's manner, often described as "Kotetsu "--straight or gently , turning back in with at the tip. The notes that his generally tends toward a coarser quality than his master's, though his superior works demonstrate that is "not so coarse" with a well-defined .
The repeatedly affirm that Nagamichi's best work "displays the area of workmanship in which Nagamichi most excelled," and multiple designations single out examples where both and are bright, sound, and well-preserved. Works bearing cutting-test inscriptions by Yamano Kanjuro Hisahide and dated examples from the Enpo and Jokyo eras provide important documentary material, including a blade dated Jokyo 2--the very year of his death--valued as a testament to his late-career output. Tradition further records that one of his blades was bestowed upon Kondo Isami of the Shinsengumi by the Aizu domain lord Matsudaira Katamori, later passing through the hands of General Tani Tateki and the Tosa Yamauchi family.