Yoshihiro (左吉弘) was a swordsmith of the Province school who is traditionally said to have been either the son of O- (-monji) or one of his leading disciples, and is further thought to have had a son, Kunihiro. The school emerged in the early period, departing from the earlier, more traditional Kyushu manner to establish a refined style characterized by a bright, clear and , strongly colored by -. Sword reference works record signed pieces by Yoshihiro dated to Shōhei 22-23 (1367-1368), establishing his active period. Among extant works, signed examples are few; signed are exceedingly rare, a consequence of the prevailing fashion for large that were later shortened and converted into .
Yoshihiro's forging shows with a tendency to flow, mixed with and ; the grain stands somewhat, and thick forms with fine and, in certain works, a faint -like effect. The ranges from shallow with and mixed in, to compositions where , , and intermingle in a gentle undulation. and enter; the is clear and bright, with adhering well, mixed at times with ; and appear throughout. The characteristically enters as with a rising tendency, becoming pointed before turning back — a distinctive feature of the lineage. and appear in the more vigorous examples, further attesting to the influence.
The formerly transmitted in the Ikeda family — the only extant signed example — possesses exceptional documentary value. The Tokugawa Jikki records that in Kyōhō 2 (1717) this blade was bestowed by the eighth shogun Yoshimune upon Ikeda Tsugumasa, and it is accompanied by an by Kochu of the year. The has recognized Yoshihiro's finest works for their "forceful and magnificent manner," with ample and sturdy, dignified silhouettes that clearly manifest the period character of the height of the era.