In Japanese folklore there is a yokai known as makuragaeshi, which translates as pillow flipper. This ghostly child spirit is believed to haunt rooms, and if you sleep there, you may wake up with your pillow flipped over, or even find it down at your feet.

Masasumi Ryukansaijin (Kyoka Hyaku Monogatari)
While most makuragaeshi are happy just to play pranks, some are reportedly far more sinister. There are accounts of people being flipped over or thrown around in their sleep, and even makuragaeshi that sit on the victim’s chest, forcing the air from their lungs or causing a sleep paralysis.

Sophie Lupas
If the victim loses consciousness, this yokai may even steal their soul, causing them to die. Makuragaeshi are believed to be the ghosts of children who have died, either in the haunted room, or in connection to the place they haunt. 

Shigeru Mizuki
So if you find little muddy footprints in your room, beware, you may be haunted by a makuragaeshi. Either that, or a tanuki is messing with you.

Sekien Toriyama (Gazu Hyakki Yagyo)
Matthew Meyer