In Heike Monogatari traditions, Raiyō’s plea to establish an ordination hall is denied, breeding resentment; after a prince’s early death, he appears as a sinister old monk. In the Engyōbon and The Rise and Fall of the Genpei, his malice becomes a great rat that devours Enryakuji’s scriptures, leading locals to enshrine and pacify it at Sakamoto. The Taiheiki exaggerates that 84,000 rats with iron bodies and iron fangs swarmed Mount Hiei, boring through Buddhist statues. Early modern lore tells of “Nezumi no Hidekura,” a site venerating Raiyō, and mounds where the Victory Jizō sealed the rat, with variants spread across the region.