Emperor Sutoku

Emperor Sutoku (崇徳天皇, 1119–1164) is considered one of Japan's most powerful vengeful spirits (goryoshin). After losing the Hogen Rebellion of 1156 against his brother Emperor Go-Shirakawa, he was exiled to Sanuki Province (modern Kagawa) where he spent years copying Buddhist sutras in his own blood, reportedly vowing to become a demon (tengu) to bring revenge upon the imperial court.

His death in exile (1164) was followed by a series of disasters and epidemics in Kyoto—epidemics, fires, and military upheavals—which the court attributed to his vengeful spirit. He was eventually enshrined at Shiramine Jinja in Kyoto to pacify his wrath, and the Shiramine Shrine in Sanuki (now Shido Jinja area) also honors him.

Along with Sugawara no Michizane and Taira no Masakado, Sutoku is counted among Japan's 'Three Great Onryo' (三大怨霊). The transformation of his wrath into protective power through enshrining represents a core pattern in Japanese goryoshin belief.