The Zashiki-Warashi sometimes also called Zashiki Bokko is a Yōkai originating from Iwate Prefecture.
The appearance of this spirit is that of a 5 or 6 year child with bobbed hair and a red face. Zashiki warashi can be found in well-maintained and preferably large old houses. It is said that once a zashiki warashi inhabits a house, it brings the residence great fortune; on the other hand, should a zashiki warashi depart, the domain soon falls into a steep decline.
As the zashiki warashi is child-like in nature, it is prone to playing harmless pranks and occasionally causing mischief. They are known for running around and making noise, even adjusting the bedding of overnight guests. Sometimes they leave little footsteps in ashes. There are different variations as to who can see the zashiki warashi; usually this is limited to inhabitants of the house, sometimes to children.
Yōkai similar to zashiki warashi in other parts of Japan include: the makuragaeshi in Ishikawa Prefecture - another creature which alters bedding; the ainukaisei in Hokkaido; and the akagantā found in Okinawa.
The Ryokufūsō in Kindaichi-Onsen, which burned down on October 4, 2009, was famed for its zashiki warashi