In Tōhoku it’s blamed on the pranks of zashiki-warashi, with tales of tiny footprints and raised tatami. Many regions say a vengeful spirit of a murdered traveler or someone who died in that room becomes a pillow-flipper. Temples tell of special “pillow-flipping rooms” and hanging scrolls that cause sleepers to turn so their heads face the principal image. Some traditions attribute the phenomenon to animals—tanuki, monkeys, or cats (kasha).