The creator of Ge Ge Ge no Kitaro is a one armed WWII Japanse vet with PTSD who lives in a house in the mountains that is a maze of hidden rooms and secret doors that two of his editors actually became lost in for several hours. He actually believes in the assorted ghosts, goblins and so on of Japanese myth.
He is also incredibly rich because this show is iconic in Japan, to the point that it's one of those properties that gets a new cartoon every ten years or so, like Spider-Man or something over here.
Apparently the manga is much darker and contains lots of surreal and horrific nightmare imagery.
He was apparently shipwrecked in Papua New Guinea, and believes wholeheartedly that people who have not been exposed to electricity can see ghosts and spirits. The puzzle house has become somewhat of a legend, and Mr. Puzzle (or whatever he's translated as in America) in the Pokemon games is directly based on him. Cool dude.
Shinto mytology can be kinda creepy and pops up in weird places (like Mario brothers games). I know that one Takashi Miike movie isn't based off this, but it reminds me of it. I must now go seek out information on this thing's elusive creator.
Woops: turns out this is what the Takashi Miike film THE GREAT YOKAI WAR was partially about, from Wikipedia:
In 2005, Shigeru Mizuki appeared in a cameo role in Yokai Daisenso ("The Great Yokai War") directed by Takashi Miike, a film about yokai inspired by his work; several of his characters make cameo appearances. A brief explanation about his works also is mentioned in the film.
Its a fun movie if you ever get the chance to see it.