Oboro-guruma is a Japanese specter of gissha (ox cart) depicted by Sekien TORIYAMA in the collection of specters "Konjaku Hyakki Shui" (Ancient and Modern Gleanings of the Haunted Demon) in the Edo period.
In the Sekien's picture, a huge woman's face with a look of yasha (Buddhist guardian deities sometimes depicted as demonic warriors) or a chagrined look is depicted in front part of a translucent oxcart where a bamboo blind is supposed to be hung.
According to the expository writing attached to it, the following is what the writing says:
Once upon a time there was a creaky sound on Kamo Grand Street on a oboro-yo (misty and moonlit night).'
It was found out that it came from a strange creature when someone went out.
It might have been the revenge of Kuruma Arasoi.'
Kuruma Arasoi' is the struggle that during the Heian period the court nobles scrambled to move their carts and park gissha in order to get better view on the occasions including festivals.
Therefore, nowadays it is interpreted as follows. Oboro-guruma is a specter that the revenge of a court noble who had lost in Kuruma Arasoi turned into. When someone jumped out of his house to hear the creaky sound of an ox cart on an oboro-yo in the street of Kamo-cho (Kyoto Prefecture) (present Kizugawa City), he found the strange creature Oboro-guruma there. It is also said that, as the word Oboro (dim) indicates, it is not something tangible that can be touched by hands, and the whole part is translucent.
According to another interpretation, Oboro-guruma is based on a specter in the "Genji Monogatari" (The Tale of Genji) in the mid Heian period that the revenge of Rokujo no Miyasudokoro who had lost to Aoi (Genji Monogatari) in the struggle to get a better place to see a festival turned into. Also, there is a story in the "Uji Shui Monogatari" (a collection of the Tales from Uji) that when a man was sleeping with a yujo (prostitute) in Ichijo Sajiki-ya (Ichijo Sajiki Store), he witnessed an ogre with horse head chanting 'Shogyo Mujo' (all things must pass) on the Kamo Street. Also, there are many stories about Hyakki yagyo (Night Parade of One Hundred Demons) such as witnessing the procession of ogre in Kyoto in many ancient documents.
Based on such facts, there is a theory that Hyakki yagyo or such sort of things were depicted as 'Oboro-guruma.'