Zashiki Warashi

It has been noted that they might be the spirits of children who were crushed to death and buried at the home. In the Tōhoku region, infanticide was called usugoro (臼殺, or "mortar kill"), and it is said that children who were killed this way to reduce the number of mouths to feed would be killed by being crushed by a stone mortar and there was a custom of burying them in the dirt floor room (doma) or in the kitchen. It is said that the spirits of such children would on rainy days walk around outer edges shaking and frightening the guests, which is said to be seen to resemble deeds similar to that of a zashiki-warashi. 

The aforementioned notabariko and usu-tsuki warashi are seen to be lower ranking among the zashiki-warashi, and the former would peek out from the inner dirt floor (doma) room and crawl around while the latter would use a mortar to make a sound. Due to such acts, it is sometimes suggested that these kinds of zashiki-warashi have a relation to the fact that the location where the infantide happened is in the dirt floor (doma) room or underneath a mortar.

In addition to this relation to infanticide, the fact that the zashiki-warashi are in both old homes and are often mentioned in relation to legends about how after a visiting Buddhist pilgrim from outside the village was killed, the family of the home came to ruin, it has been suggested that these zashiki-warashi are signs of the dark undersides of the village's community.

There are also stories about zashiki-warashi that came about from a curse that resulted from carpenters and tatami makers that were unable to do their construction jobs in comfort, and it is said that there were rituals of taking a doll that had a bit of its wood peeled off and inserting it between the pillars and beams.

There are many theories that their true identity is that of a kappa, whether that be a kappa that lived in the depths who would rise up and go into a nearby home to do pranks, or zashiki-warashi that were kappa that have settled into a home.

In Buddhism there are gōhō-warashi (wrathful gods that protect Buddhism and take on the appearance of a child), which may explain why they appear to like children. There is the theory that they come from folk beliefs in how children connected gods and humans, as well as the theory that the appearance of a child embodies divinity.

The protective spirits of Buddhism and folk mikos are related to the faith in giving respect to the freshness of the spirits of young leaves, and this is related to the faith in the zashiki-warashi who became protective spirits of a home in order to will divinity to humans. In folkloristics, there has been debate on subjects such as the relation to Okunai-sama and the relation of children that come from another realm such as the Ryūgyū-warashi (dragon palace warashi).

Zashiki-warashi have almost all their characteristics in common with animal spirit possession such as izuna-tsukai ("weasel-using"). From an analysis of the supremacy and inferiority within the community of families with a spirit haunting them, zashiki-warashi have been used as a basis for explaining changes in fortunes within folk society, especially for old homes and families.

In Iwate, there are legends of how the zashiki-warashi of a shrine at Hayachine would follow a shrine visitor who came from afar and follow them into different lands. There are also legends of how the zashiki-warashi would teach the nursery rhyme of Iwate to the children of those lands.

In Gonohe, Aomori Prefecture, there is a legend of how when a new house is built, a zashiki-warashi can be called into it by burying a golden ball under the floors.

Despite there being many legends of the zashiki-warashi in the Tōhoku region, there are fewer in Akita Prefecture; this is said to be because Akita has the sankichi oni, so lower-class yōkai would not enter Akita.[6]

There are stories about how when adults counted children, there would be one more person than there was originally, but as adults do not understand what zashiki-warashi are, they would not know who the extra person is.

Families with zashiki-warashi would prosper and families whose zashiki-warashi have gone away would decline. In this aspect the Zashiki-warashi are like gods of fortune or protective spirits that rule over a family's prosperity and decline.

There is the theory that a white zashiki-warashi is a sign of good things to come and the sight of a red one (with a red face, red clothes, and a red bucket in its hands) is a sign that a zashiki-warashi would leave the family leading to bad things to come.

They are said to like azuki meshi, so there are families that offer some azuki meshi every day, and if it is not eaten, it is said to be an omen for the family's decline.

Zashiki-warashi generally work the same way as having kitsune or inugami, except they are never considered a nuisance.

In the area around the city of Ninohe, there is a custom of making up a room with desserts and toys left inside for a child who had died or was killed as an infant, and giving worship to this child, a custom that remains to the present day. 

There is also a custom of making a room that a child would like in order to make a zashiki-warashi stay at the house in order to bring the family prosperity.

Tales of zashiki-warashi are still common in the modern era, having been found in Meiji, Shōwa, and beyond.

In many homes, these spirits befriend the children of the house, teaching them songs, games, and nursery rhymes. 

They keep elderly or infertile couples company, and these couples often treat it as if it were their own child. 

The desire to attract and keep these friendly yōkai has led to customs like setting out food in the zashiki for them, and even laying coins in the foundation when building a new house. The Japanese take great care to maintain their formal reception room so as not to drive out any guardian spirits dwelling there.

There are a few different variations and ranks of this youkai, and not all of them are found in the tatami guest room that their name ‘zashiki’ implies. Some zashiki-warashi variations are said to have no influence on the family's fortunes and instead merely move around the house making noises, and a good few have been deemed just plain creepy.

• Zashiki-warashi in a home's dirt floor are called kometsuki-warashi, notabariko, usutsuriko, among other names.
• The white, most beautiful zashiki-warashi that is in the inner zashiki is called the chōpirako.
• The hosode or hosode nagate have arms that are long and thin like vines, which they use to beckon people as well as warn of disasters like floods and tsunami.
• There is a story telling of how "a poor man once threw firewood into the water, was invited into the dragon palace, and received as a gift an ugly-looking but fortune-bringing ryūkyū-warashi (dragon palace child)". 
• Zashiki-warashi that stay in the dozō are called kura-warashi or kura-bokko (child of the storehouse).
• A certain kabukire-warashi (tree stump child) lives in the "Mada no Ki" (meaning "Bodhi tree"). It is said to take on the appearance of a child and sneak into the family's zashiki to perform pranks on the family's daughter, as well as take on an appearance with a red face and play on walnut trees where the tree splits into three. It has also been interpreted to be a spirit of this Mada no Ki.
• Near one of the inner temples of the Kotohira-gū in Shikoku, it is said that at nighttime an "akashaguma" appears from a butsudan. "Akashaguma" refers to the fur of a bear that has been stained red, and it is said that a little childlike being wearing this would tickle the old woman owner of this house every night.
• An okura-bōzu ("warehouse bonze") that stays within the warehouse, and is thought to be a type of zashiki-warashi.
• In Hokkaido there is the ainukaisei said to attack people in their homes while they sleep, and in the Okinawa Prefecture there is a yōkai called the akagantaa said to play pranks on people in their homes while they sleep, and sometimes these are interpreted to be the same kind of beings as zashiki-warashi.
• Folklorist Shinobu Orikuchi enumerates examples such as the okunai-sama, the zashiki-bōzu, the akashaguma, the kijimuna of Okinawa, gaataro of Iki, etc., and sees in them examples of tales of a faithful spirit that came from another land to do work for a certain family whose disappearance would result in the decline of the family.　He notes how zashiki-warashi do not descend into the garden and suggests that this is related to how performing arts in the past had a division between "garden", "zashiki", and "stage"