A BRONZE SCULPTURE OF KOKI (REAR-GUARD DEMON)

Ascetics were entering mountainous areas of Japan for the practice of austerities at least as early as the Nara period. They are generally known as shugenja, meaning those who accumulate power or expertise through severe ascetic practices such as fasting, seclusion, meditations, magical exercises and the like. They were not necessarily Buddhist monks, but included various hermits and wandering religious figures. The most famous of these ascetics was En no Gyoja (b. 634), revered as the founder of the shugendo sects. He operated mainly in the Katsuragi-Yoshino and Kumano regions. It is said that he arrived in this area at an early age, studied the secret magic formulae of esoteric Buddhism and Daoism and attained miraculous powers.
He is often depicted as a central figure of a triad with two servant-demons, Zenki (fron-guard demon) and Koki (rear-guard demon). This pair of demons is believed to be a couple, Zenki the husband and Koki the wife. While Zenki holds axe in hos hand, Koki carries vase filled with sacred water and medicine in her backpack.