Onjoji (Miidera)おんじょうじ

A version grounded in medieval tales where the spirit of the monk Raiyō becomes a swarm of rats or a monstrous iron-furred rat known as the Tesso and gnaws through the sutra repository of Enryaku-ji. Rivalries among temple powers are projected onto a narrative of vengeful deification, linking ritual efficacy with retribution. In literature it appears mainly in war chronicles, blending a real monk’s biography with a settled ghost-vengeance legend. Later yomihon and paintings amplified this image, symbolizing rat blight and the ruin of sutra scrolls, yet at its core lies a folk pattern of a rancorous spirit bringing calamity upon sacred objects and scriptures.

Based on Toriyama Sekien’s “Tesso” motif, it appears as a giant rat draped in robe-like shadows, with red eyes and teeth said to be iron-hard. Its origin lies in the vengeful spirit tale of Raigō tied to disputes over the ordination platform at Onjōji, where rivalry between Enryakuji’s Sannō faction and the Miidera side was cast into story and overlapped with real rat damage to temple sutras and treasures. Names vary by period and source, with “Raigō Nezumi” and “Miidera Nezumi” coexisting. Medieval war tales exaggerate its numbers into a calamity of swarming rats, while from early modern times it links to shrine legends of pacification and blessings. Chronologies in records do not always align and the tale is highly narrative, yet shrine and temple names, linked verse, and oral lore support a core tradition. In some regions, extermination stories feature a great cat of Mount Hiei or guardian deities, reflecting the boundary-conscious rivalry between two religious centers.