I think most people with knowledge to "Yokai" spirits will follow my passion for this obscure universe of folklore.
I just finished reading this book 学校の怪談 which means "school of ghost stories" and its made as a encyclopedia containing almost every ghost from japanese folklore all from Kappa to Gegege-no-Kitaro and Nezumi Otoko (ねずみ男, in english="Rat Man")
I have since long ago studied this, and started watching Gegege no Kitaro from the 60's and this certain series might be the only Anime I've ever really liked because its takes up serious historical facts and problems like second world war and the black death.
These three colored pictures are taken from a art journal I bought few months ago at one of Uenos many museums.
If you feel more interested in This Yokai mania.
Please watch some of the old openings for the tv series from the past.
Its very retro.
And a trailer from The newly made Gegege movie and Takashi Mikes "The Great Yokai War"