応仁後の山城鍛冶衰退期

The Ōnin War (1467–1477), fought almost entirely within Kyoto itself, inflicted catastrophic damage on the Yamashiro smithing tradition. The workshops of the Rai school, Awataguchi school, and other great Yamashiro lineages were burned down and their communities scattered. Surviving smiths fled to the provinces, attempting to rebuild their craft under the patronage of regional warlords—but the intricate techniques that had made Yamashiro swords the pinnacle of Japanese craftsmanship—tight ko-itame jigane, deep nie suguha hamon, and exquisitely shaped nakago—proved very difficult to reproduce without the intact master-apprentice chains and established workshop infrastructure. Post-Ōnin Yamashiro blades, classified as sue-kotō (late old swords), are generally considered inferior to the school's Kamakura-period height. Meanwhile, Bizen province's Osafune workshops, unaffected by Kyoto's destruction, expanded into the role of Japan's dominant sword-production center; and Mino's Seki smiths rose to supply practical blades to the down-to-earth warriors of the Sengoku era. The historical lesson of this period—that cultural infrastructure, once destroyed, cannot simply be rebuilt—made the Ōnin War's cultural damage one of the most mourned losses in Japanese art history.