百鬼夜行
ひゃっきやぎょう

Translation: the night parade of one hundred demons
Alternate names: hyakki yakō
Habitat: travels throughout Japan, appearing on inauspicious nights each month

Appearance: The hyakki yagyō is the dreaded night parade of one hundred demons—an event when all of the yōkai, oni, ghosts, tsukumogami, and other supernatural creatures leave their homes and parade through the streets of Japan in one massive spectacle of utter pandemonium. In many ways, it resembles a traditional Japanese festival, filled with songs and chants, dancing, and merriment. The parade is said to be led by nurarihyon, nozuchi, and otoroshi.

Interactions: Humans foolish enough to go outside on these nights, or curious enough to peek out of their windows in hopes of catching a glimpse of the supernatural, are either killed or spirited away by the monsters. This is attributed sometimes to divine punishment for looking upon that which must not be seen, and sometimes to sheer shock from witnessing this horrible spectable.

Legends: According to the Shūgaishō—a medieval Japanese encyclopedia—the only way to keep safe from the night parade should it come by your home is to stay inside on the specific nights associated with the Chinese zodiac on which the night parade is said to be held. Those who hear the pandemonium parade pass by their homes should chant this magic spell:

KA-TA-SHI-HA-YA, E-KA-SE-NI-KU-RI-NI, TA-ME-RU-SA-KE,
TE-E-HI, A-SHI-E-HI, WA-RE-SHI-KO-NI-KE-RI