Yasuyoshi, traditionally identified as the son of O- (), succeeded as the second generation of the lineage in Province during the period. He is said to have later relocated from to Choshu (Nagato Province), a tradition "readily accepted" by the on the basis that a dated Shohei 17 (1362) and inscribed "Choshu-ju Yasuyoshi" — designated an Important Art Object — bears a manner of inscription identical to his customary signature style. Thereafter, works explicitly stating "Choshu Yasuyoshi" survive with dates from the Eiwa and Oei eras; the Oei-dated examples are, from both workmanship and signature style, "clearly to be appraised as the work of a successor generation," while whether the Eiwa-dated pieces represent late works of the first generation or productions of a successor "remains a subject for future research." His descendants settled in Choshu and continued the name into the period. Among extant signed works, no firmly established survive; his oeuvre is limited to and small , which — reflecting the character of their time — commonly assume a larger, broader scale than the compact forms favored by his father.
Yasuyoshi's forging typically shows mixed with and , with the grain standing out (); thick adheres, enter well, and a straight or whitish — often described as — is a recurring feature. The , while clear, is characteristically "not as clear as 's." His is mixed with , , and , rendered in a -dominant manner with and accompanied by fine and . The repeatedly identifies his defining trait as a temperament "in which elements are intermingled" within the broader group — to the extent that "at a glance the style can be mistaken for works such as those of Kanemitsu." The is among his most distinctive features: rising in , inclining toward the edge, becoming pointed with , and turning back long — a "forceful impression" that the considers a hallmark of the lineage. On certain works, a deep, softly inflected carrying a pronounced -ai ("salt-like" texture) draws particular attention, producing rich variation together with the abundant internal activity of the tempered edge.
The situates Yasuyoshi as a figure whose workmanship "clearly displays the strongly -flavored working range that is a hallmark of the first-generation Yasuyoshi," distinguishing him within the ichirui (-related group) by this characteristic admixture of sensibility. His finest examples are praised as works in which "Yasuyoshi's distinctive strength can be strongly felt," with individual pieces lauded as "especially outstanding" and "flawless and representative." The earliest works approach O- so closely in shape and quality of and that they display "workmanship that is truly liable to be mistaken for O- himself, revealing an exceptionally distinguished result" — a quality the terms shussoku. Pieces showing thickly adhering throughout both and , with a bright and clear and a flame-like , are described as "filled with vigorous spirit" and reminiscent of O-'s own hand. Whether certain early signed works constitute evidence that O- himself occasionally inscribed the name "Yasuyoshi," or whether they represent Yasuyoshi's earliest productions, they remain "valuable material that urges further investigation" — a testament to the intimate continuity between master and successor in this most distinguished branch of the school.