According to Japanese belief, Yanari are miniature oni which appear in houses late at night. They appear most often in wooden houses — especially those of cheap or new construction in which all of the parts have not had time to settle yet. They often carry miniature weapons or tools, such as mallets or iron clubs.

Yanari only do one thing, and they love doing it: making noise. They come out from the floors, ceilings, and the woodwork late at night when everyone is in bed, and they run about the house performing mischief. Specifically, they bang the furniture, the walls, floors, ceilings, and anything else they can find. Occasionally they even break objects, although their activity is usually non-destructive. Yanari delight in the work, and take it very seriously. Although tiny, they have a strong work ethic and do their best to perform their duty of making noise to the fullest.

Long ago, in what is now Hyogo, a group of ronin decided to test their courage by spending a night in a haunted house. Late at night, when they were all fast asleep, the entire house suddenly began to shake violently. The ronin, thinking it was an earthquake, dashed outside for safety, however they soon realized that it was only the house that was shaking…

The next day the group of ronin visited a wise man who lived nearby and told him of their experience at the haunted house. The wise man offered to stay with them that night to see for himself. Sure enough, late at night, the entire house began to shake violently just as before. The wise man looked carefully at the floor. Locating the area where the most violent shaking was originating, he stabbed his dagger deep into the tatami mat. Suddenly, the shaking stopped entirely.

The next morning, the ronin and the wise man examined the house. Under the floor where the wise man had stabbed his dagger, they found a strange gravestone dedicated to the memory of a bear. Where the knife had penetrated the stone tablet, blood was trickling out.

The wise man asked others in the neighborhood what the strange gravestone could mean, and they explain that some time ago, there was a bear in these parts who frequently broke into peoples’ houses at night. One night it broke into that particular house, and the man who lived in there killed it. In order to appease the spirit of the bear he killed and protect himself from the vengeful ghost of the bear, he had a gravestone placed in the house dedicated to the bear’s memory. The ghost of the bear must have possessed that gravestone, which is what had been causing the yanari to appear every night and shake the house for years.