In Japanese Folklore, the Ashiarai Yashiki is a giant filthy foot that crashes through the ceiling at night and demands to be washed. If you don't wash it, it will rampage through your house pic.twitter.com/MBwalGWFDZ— 41 Strange (@41Strange) March 26, 2018
Japanese monster stories are so bizarre that it's hard to know whether they are old or were made up for some modern manga, but Ashiarai Yashiki is apparently a real legend. According to the Villains Wiki,
The Ashiarai Yashiki is an extremely bizarre Japanese spirit that takes the form of a disembodied leg and foot, many times larger than a normal human and often covered in mud or blood - this frightening being was believed to literally smash its way into the homes of terrified humans and demand them to wash it.The only way I can picture this happening is in a Terry Gilliam animation. You have to wonder if he was familiar with the legend of Ashiarai Yashiki. (via madamjujujive)
The reason behind this attack was unknown and most likely could never really be understood as spirits such as the Ashiarai Yashiki were believed to be governed by laws far beyond human understanding, yet even by Japanese mythology standards the Ashiarai Yashiki stands out as one of the more unique monsters of folklore and despite being little more than a giant foot it was capable of human speech.