An incomplete but growing list of the monsters by Kikuno as far as they are described on that site. Please keep in mind that errors and misunderstandings on my side are highly possible.
Many of the monsters are taken from the "One Hundred Stories of Demons and Spirits", some are direct edits from old woodcuts. If you are interested in these legendary creatures, you might want to check out the "Edo" monsters.
Red Tongue. This creature lives in rivers.
A very annoying ghost that cuts mosquito nets in summer, or fishnets.
Blue paper-covered lamp stand. This is the ghost that appears when the last story is told and the last light goes out, if I understood it correctly.
Azuki bean washing. A ghost that does not show, just makes a sound. It is assumed that it is a little old person.
Another ghost associated with the Azuki bean, an old woman. Seems to be somewhat more dangerous.
Transforming Cat. Note the split tail.
Transforming straw sandals. There are lots of spirits that mimic innocuous objects.
Some sort of enormous chicken that flaps around your house at night.
Suddenly plunging into their necks, this ghost causes people to lose all courage.
Literally, this means something like "Hundred Eyes". Multi-eyed monsters are popular in Japanese folklore. According to kikuno's text, this one is a pick-pocket, or the ghost of a dead pick-pocket, I'm not quite sure. Filename: dodo.
Hungry Ghost, from Buddhist tradition. Greedy people turn into these ghosts after death, their punishment is similar to that of Tantalus.
Picture spirit: the person drawn on the picture becomes a ghost.
This ghost absorbs candle flames and camp fires, leaving you in the cold and dark.
Some sort of boneless creature.
Wind God. He brings plague and poor harvest. The white cloth is the sack he carries the winds in. His name is also transscribed as Fujin.
This ghost will transform into a human to get your trust. If you are careless, it will steal all your belongings (that's what the huge sack is for).
This ghost causes the sound of wood being cut, and of falling trees.
This creature lives in Lake Kamo in the Niigata prefecture. Underwater, it is invincible.
Sickle Weasel. They move so fast that nobody ever got a look at them. Kamaitachi live in the mountains of northern Japan and always attack in packs of three. The first knocks the victim down, the second slashed him, the third heals his wound. All that remains is a scar that neither bleeds nor hurts.
Chinese umbrella (?).
A mischievous wood spirit living in a large forest in Okinawa prefecture. Also called Kijimuna or Bubagaya.
Neck Nibbler, another type of hungry ghost.
Black demon mirror.
Mountain Giant (Yama Kyochin). Usually friendly, he becomes very dangerous when angered.
This monster is directly taken from an old woodcut. The literal translation is eye competition, and it is somehow linked with a historic event from 1170.
Wry Smile. This ghost appears when a deceptive, ill-meaning person laughs.
Meat Inhaler. This ghost takes on the form of a young woman (17 or 18 years old), and if you go to near, it inhales the meat of your whole body.
A ghost lurking in deserted temples.
This spirit lurks on the roofs of shrines, or on the torii, ready to drop down on people not behaving appropriately, killing them in the process.
Thunder God. The small round objects around him are the drums he uses to make the thunder.
The spirit of a murderer, it dives into a well or drops you into a well, I'm not quite sure which. A search for sakayure returned absolutely no results, so I'm still a bit mystified.
Mountain Spirit. About the size of a child, it can run very fast, cause sickness and burn houses. The etymology of the filename is unclear; sansei is usually the term for a third-generation Japanese American.
Stemming originally from India, this is something like a zombie, a walking corpse.
The name obviously cannot be translated. Old dustcloths or mosquito nets, when neglected, become this ghost.
Literally "High Woman", a spirit that lives on the upper floor of a house (traditionally the women's quarters).
A ghost that dangles from the ceiling at night upside-down and scares people. Filename is tenjos.
Iron Mouse. This is something from Buddhist tradition, especially connected with the Mitsui temple in Shiga prefecutre.
Greedy old women who steal the oil from the eternal light turn into this mysterious fire ghost, which appears on days with light rain.
a large head that appears suddenly before boats.
If you see this ghost, a wheel with a face in the center, your life is lost.
Old Lady of the Willow. She resides in an old willow, can turn into an old woman or a beauty.
Snow Woman. She is beautiful but cold. If you go too near you will freeze to death.