This is the third post on the yokai sculptures on the Mizuki Shigeru Road. Details in Yokai Gallery 1
Salaryman Yamada is not, as far as I can tell, a yokai, but he is a character in Mizuki Shigeru's work, and is based on a friend of his.
Omotogami is another name for Omotojin, also known as Kojin in neighboring Izumo. I was surprised to see it classified as a yokai as it is in fact a common kami in this part of the world. It is often known as an aragami, which is usuually translated as "rough deity", but I prefer the translation "turbulent deity", as it is a force of nature and quite capable of causing damage. More posts on Omoto here
These are Shigeru's creation, Daruma and guts, and are based on the well-known Daruma, who was the Bodhidharma who brought Zen (Chan in Chinese) from India to China. In his common form he has no arms or legs as they have atrophied from years of sitting in meditation. In Shigeru's daruma, the little creatures are daruma's "guts", and if they are killed Daruma becomes weaker.
Uwan is an invisible Yokai that inhabits old houses and temples. His shouts can only be heard inside the building. In the Edo period artists began painting images of various "invisible" yokai.
Medama Oyaji is the father of Kitaro, Shigeru's most famous character. A ghost reborn as just an eyeball, the character is known as Daddy Eyeball in the english version. He loves to stay clean and is often found bathing in a bowl.
Keukegen is completely covered in hair and is known to cause disease in humans. It inhabits damp, airless spaces, so the solution is to open windows and doors and allow some air circulation.
Yamabiko is a tree spirit living in the mountains that creates the echoes you hear in the mountains.
Syunobon is a yokai originally from Fukushima. When following you he appears human, but will startle you by reverting to his original form.
Aonyoubou (Blue Wife) is a form of Goryu, an "angry ghost". The most famous Goryu is Michizane Sugawara, commonly known as Tennjin. Humans killed for political reasons are particularly prone to be angry ghosts.