Aili and I found this while putzing around Drawn!
Yōkai Daizukai, an illustrated guide to yōkai authored by manga artist Shigeru Mizuki, features a collection of cutaway diagrams showing the anatomy of 85 traditional monsters from Japanese folklore (which also appear in Mizuki’s GeGeGe no Kitarō anime/manga).
The Makura-gaeshi (”pillow-mover”) is a soul-stealing prankster known for moving pillows around while people sleep. The creature is invisible to adults and can only be seen by children. Anatomical features include an organ for storing souls stolen from children, another for converting the souls to energy and supplying it to the rest of the body, and a pouch containing magical sand that puts people to sleep when it gets in the eyes. In addition, the monster has two brains — one for devising pranks, and one for creating rainbow-colored light that it emits through its eyes.
More to be found at Pink Tentacle.