The first-generation Onizuka Yoshikuni (鬼塚吉国) is said to have originated from Tanakura in Ōshū and to have relocated to Yanagawa in Chikugo Province by relying upon Yufu Iki-no-Kami, chief retainer of the Tachibana house. Several generations bearing the name are recorded in this region thereafter. Extant dated works by the first generation are exceedingly rare; however, the survival of a inscribed "'ei 17th year, 8th month" establishes his active period as the early era.
Works by this smith that are ordinarily encountered tend to be -toned pieces close in manner to swords. However, the examiners consistently observe that, compared with blades, the is not as deep and there is often a sense that the brilliance () is somewhat lacking. The finest designated examples depart markedly from this general assessment: their is deep -- at times surpassing work -- with adhering well, some coarser intermingled, and and producing a bright . The is characteristically with shallow , mixing , , and , features that suggest an intent directed toward older Yamato works. One blade exhibits deliberately shaved away from the base upward, further reinforcing this archaic aspiration.
The forging presents tightly worked with fine, dense and entering well. The of his conveys considerable force: wide with a sense of , deep curvature, and extended . One piece, constructed with particularly deep , was likely intended as a jin-dachi for battlefield use. The examiners single out his as the form in which Yoshikuni's true strengths are fully manifested, praising his finest work as both and of exceptional quality in and .