According to Wikipedia, Yōkai is a broad terms for a class of monsters and supernatural beings in Japanese folklore. In the 1960s, a manga artist by the name of Shigeru Mizuki created the Yōkai Daizukai, an illustrated guide that takes a look inside the humorous or bizarre characters that inhabited the Japanese countryside.
Have a look at a few of the cutaway diagrams after the jump.
This is the Kuro-kamikiri, a large monster that sneaks up on women in the night and cuts off their hair. This fetishist has razor-sharp claws, a coiled tongue covered in tiny hair-grabbing spines, and a sac for storing sleeping powder used to knock out its victims.
The Mannen-dake is a 10,000 year-old monster that feeds upon the souls of travellers lost in the woods. The creature inserts its syringe-like fingers into the victims to suck out their souls.
The Fukuro-sage can shape-shift into a sake bottle. Proving that drinking is for your health, the Fukuro-sage rolls down sloping streets or hillsides, tempting its victims to give chase, and hoping they fall off the edge of a cliff or into a ditch. The monsters also carries a bag made from human skin and its urine can disorient humans.
Find more bizarre Yōkai cutaways at the Pink Tentacle.