Zenki and Goki (Ogre in front and the one in back) (前鬼・後鬼)
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. Zenki is the husband and Goki the wife.
In the sculptures and pictures of EN no Ozunu, Zenki and Goki are often (not always) depicted in his right and left. They are mostly depicted as a ko-oni (little ogre), a little smaller than EN no Ozunu.
Summary
They are also called Zendoki and Myodoki. Zenki is also called Gikaku or Gigaku, and Goki is also called Gigen or Giken.
It is said that they were Shikigami (the spirit using magic or divination) used by EN no Ozunu, and they were sometimes regarded same as Gikaku and Gigen who were supposed to be En no Ozunu's disciples (their substantiality and the actual relation are unclear).
Zenki, the husband is a red ogre, representing yang of yin-yang, with an iron axe, and goes in front of EN no Ozunu and clears the path as the name shows. He mostly carries an Oi (wooden box carried on one's back to store items for a pilgrimage) on his back. It is said that he was from the present Shimokitayama-mura, Yoshino County, Nara Prefecture.
Goki, the wife is a blue ogre (also depicted as blue green), representing yin, with a jug of Risui (water with psychic power), and she mostly carries seeds in an Oi on her back. It is said that she was from the present Amakawa-mura, Yoshino County, Nara Prefecture.
Zenki and Goki have A-Un (inspiration and expiration, or alpha and omega) relationship. Though, thinking of yin-yang, Zenki is regarded as A (with the mouth open) and Goki as Un (with the mouth closed) in nature, it is sometimes reversed.
Tradition
They used to live in the Ikoma Mountain Range, and caused harm to people. EN no Ozunu captured them by the secret art of Fudo Myoo (Acala, one of the five Wisdom Kings). Or he hid the youngest child of their five children in an iron oven, by which he made them know the sorrow of the parents whose child was killed. The two mended their ways, and obeyed EN no Ozunu. The name Gikaku (Gigaku) and Gigen (Giken) were given by EN no Ozunu then. The mountain where they were captured is called Onitoriyama or Onitoridake (ogre-capturing mountain), and located in the present Onitori-cho, Ikoma City.
There is also a legend in Subashiri-mura, Oyama-cho, Shizuoka Prefecture that EN no Ozunu subjugated and was accompanied with Zenki and Goki.
It is said that they lived in the present Zenki, Shimokitayama-mura at the foot of Mt. Omine, the sacred mountain of Shugendo. There are allegedly their grave there.
It is also said that they had five children there (it conflicts with the Mt. Ikoma episode in time ordering though.)
Five ogres
The five children of Zenki and Goki were called Goki (五鬼, five ogres) or Gobo (五坊, five boys).
Their names were Shingi, Gitsugu, Gijo, Gitatsu and Gigen. (真義,義継,義上,義達,義元)
They are sometimes regarded same as Gikaku, Gigen, Gishin, Jugen (寿玄) and Hogen (芳玄), the great five disciples of En no Ozunu (Gikaku and Gigen are same persons with the disciples regarded same as Zenki and Goki though).
They opened shukubo (lodgings in a temple) for practitioners of austerities in Shimokitayama-mura, which were named Gyojabo, Morimotobo, Nakanobo, Onakabo and Fudobo. They also became the founders of the five families, Gokitsugu, Gokikuma, Gokijoh, Gokijo and Gokido respectively. The five families kept the shukubo by having marital relation to each other, and sons of the five families had the character Gi (義) in their names for generations.
However, when Shugendo declined with Haibutsu-kishaku (a movement to abolish Buddhism) in the early Meiji Period, and especially by the law banning Shugendo in 1872, three families, Gokikuma, Gokijoh and Gokido closed the business and left the village, and later, the Gokitsugu family also closed the business. Only the Gokijo family of Onakabo still has shukubo now, and Yoshiyuki GOKIJO is the 61st family head.