The Senjuin school (Senjuin-) stands among the five great Yamato traditions, transmitted to have originated in the late period near the Senjudō hall on Mt. Wakakusa in Nara, where artisans working in proximity to the Senju Kannon shrine formed this distinct lineage. Early masters Yukinobu and Shigehiro are recorded in traditional texts, though no confirmed works by either survive; for reasons unknown, the school produced remarkably few signed pieces throughout its history, rendering extant examples exceptionally valuable as documentary evidence. The collaborative work by Nobuzane—son of Yoshiyuki—and the otherwise unrecorded Shūsei demonstrates that the tradition remained active into the mid- period, while the signed by Kuchihiro, dated Jōwa 4 (1348), confirms continuity through the era.
The Senjuin technical signature emerges clearly in forging that exhibits flowing tending toward , with thickly applied adhering well to create a textured ground; the characteristic consists of -based temper incorporating and , with coarse clusters, , and distributed throughout. The Nobuzane-Shūsei displays quintessential mid- proportions with shallow and , while the school's demonstrate robust construction with high and wide , their archaic -otoshi and areas of and uchi-noke revealing unmistakable Yamato provenance. The orderly straight temper combined with sturdy, powerful form distinguishes these works from the more refined aesthetics of later traditions.
The Senjuin legacy lies not in prolific output but in its position as the earliest of the Yamato schools, establishing forging and tempering conventions that would influence subsequent generations. The scarcity of signed examples renders each surviving piece—whether the collaborative or the dated —an irreplaceable reference for understanding the development of Yamato workmanship from the late through periods. The Kuchihiro , published in Kōzan , exemplifies the documentary value these rare works possess for scholars tracing the evolution of provincial sword-making traditions.