Hyakki Yagyo; variation: hyakki yako; (lit. 'Night Parade of One Hundred Demons') is a concept in Japanese folklore. It is a parade which is composed of a hundred kinds of yokai (supernatural monsters).

Legend has it that every year the yokai Nurarihyon; will lead all of the yokai through the streets of Japan during summer nights. Anyone who comes across the procession will perish or be spirited away by the yokai; unless protected by handwritten scrolls by anti-yokai onmyoji spellcasters.

According to the account in the Shugaisho; a medieval Japanese encyclopedia; the only way to be kept safe from the night parade if it comes by your house is to stay inside on the specific nights associated with the Chinese zodiac or to chant a magic spell. Pictures From History