From the mists of prehistory to the present day, Japan has always had stories of fantastic monsters. There are women with extra mouths in the backs of their heads, water goblins whose favorite food is inside the human anus, elephant-dragons which feed solely on bad dreams, baby zombies, talking foxes, fire-breathing chickens, animated blobs of rotten flesh that run about the streets at night, and the dreaded hyakki yagyo: "the night parade of one hundred demons"—when all of the yokai leave their homes and parade through the streets of Japan in one massive spectacle of utter pandemonium.

What are yokai? Put simply, they are supernatural creatures of Japanese folklore. The word in Japanese is a combination of yo, meaning "bewitching," and kai, meaning "strange." The term encompasses monsters, demons, gods (kami), ghosts (bakemono), magical animals, transformed humans, urban legends, and other strange phenomena. It is a broad and vague term. Nothing exists in the English language that quite does the trick of capturing the essence of yokai.

This field guide contains over 100 illustrated entries covering a wide variety of Japanese yokai. Each yokai is described in detail—including its habitat, diet, origin, and legends—based on translations from centuries-old Japanese texts.

This book was first funded on Kickstarter in 2011 and then revised in 2015.