Zenki and Goki refer to an ogre couple which EN no Ozunu (A semi-legendary holy man noted for his practice of mountain asceticism during the second half of the seventh century), a founder of Shugendo (Japanese mountain asceticism-shamanism incorporating Shinto and Buddhist concepts), was accompanied with.
前鬼・後鬼（ぜんき・ごき）は、修験道の開祖である役小角が従えていたとされる夫婦の鬼。