Here are a few examples of creatures from Japanese folklore. The illustrations are from Hokusai's Manga Vol. 3. I appreciate Hokusai's art for its dynamic qualities, something shared with Mignola's work. Here we have a "Rokuro-kubi." Also appearing as normal humans during the day, they go to great lengths to disguise their true forms. Though their innate urge to scare humans often wins out in the end.