This unsigned sun-nobi tantō measures 37.3 cm (14.7 in.) in blade length with a gentle 0.8 cm sori, exhibiting the broad and powerful proportions characteristic of early Koto workmanship. Forged in hira-zukuri form, the blade features a generous 3.0 cm mihaba with only moderate taper toward the point, creating a robust and dignified sugata typical of longer medieval Japanese daggers.
The blade displays a refined suguha-based hamon with subtle ko-notare undulations, executed primarily in nioi, giving the temper line an elegant and restrained appearance. The jihada exhibits a distinctly old-fashioned texture with visible forging activity, reflecting the traditional hand-forged construction associated with early Japanese swords.
Based on its overall sugata, proportions, and workmanship, the blade is most likely attributable to the late Koto period, probably dating from the late Nanbokuchō to the early Muromachi period (late 14th to early 15th century). The overall style also shows characteristics reminiscent of the Yamashiro and Yamato traditions.