These interesting illustrations come from the book Yōkai Daizukai by manga artist Shigeru Mizuki, and they show cross sections from 85 'Y
I wish I was able to read Japanese so that I could buy myself the book, as they are both hideous and fascinating.
Here are some translated exerts for you to enjoy:
The Hyōsube, a child-sized river monster (a relative of the kappa) from Kyushu that lives in underwater caves, ventures onto land at night to eat rice plants. The monster has a relatively small brain, a nervous system specialized in detecting the presence of humans, thick rubbery skin, sharp claws, two small stomachs (one for rice grains and one for fish), a large sac for storing surplus food, and two large oxygen sacs for emergency use. A pair of rotating bone coils produce an illness-inducing bacteria that the monster sprinkles on unsuspecting humans.
The Mannen-dake ("10,000-year bamboo") is a bamboo-like monster that feeds on the souls of lost travelers camping in the woods. Anatomical features include a series of tubes that produce air that causes travelers to lose their way, syringe-like fingers the monster inserts into victims to suck out their souls, and a sac that holds the stolen souls.
The Kuro-kamikiri ("black hair cutter") is a large, black-haired creature that sneaks up on women in the street at night and surreptitiously cuts off their hair. Anatomical features include a brain wired for stealth and trickery, razor-sharp claws, a long, coiling tongue covered in tiny hair-grabbing spines, and a sac for storing sleeping powder used to knock out victims. The digestive system includes an organ that produces a hair-dissolving fluid, as well as an organ with finger-like projections that thump the sides of the intestines to aid digestion.
The Kijimunaa is a playful forest sprite inhabiting the tops of Okinawan banyan trees. Anatomical features include eye sockets equipped with ball bearings that enable the eyeballs to spin freely, strong teeth for devouring crabs and ripping out the eyeballs of fish (a favorite snack), a coat of fur made from tree fibers, and a nervous system adapted for carrying out pranks. The Kijimunaa's brain contains vivid memories of being captured by an octopus - the only thing it fears and hates.