Demon World

The Demon World is the main setting of The Promised Neverland. The Demon World is part of the world that many years ago, was split into two between humans and demons after The Promise was signed with the Ratri family. The part of the world belonging to the demons is comprised of many bizarre ecosystems and creatures, some of which include feral/bestial demons.

History
{{Spoiler Section|Text = Millennia ago, before the construction of plantations, both demons and humans shared the same world, which led to frequent hunting of humans by the demons. Some humans soon after did the same, while the rest worshipped them out of fear of getting eaten. This became a continuous cycle as both sides killed and feared one another. After countless violent wars and massacres, a clan of humans called the Ratri family stood up to the demons and made a treaty known as The Promise.{{Cite}}

Bayon's Proposal
Bayon and the government of demons held a meeting, discussing how they should consume orphans when they are forbidden to do so after the Ratri clan's proposal of a treaty. Bayon came out with the solution of building the farms to "cultivate" the young of the humans so as to satisfy the demons' need of consuming human flesh, as well as to comply with The Promise. Therefore, Bayon's solution was accepted and included as part of the treaty.

The humans gave some of their children to the demons as a parting gift when they fled from the demon world. The children were later kept in "plantations" (institutions that take care of the children) as livestock for the demons to consume.

The Signing of the Treaty – The Promise
We shall make a treaty as follows: "Human beings shan't hunt 'demons' anymore. In return, 'demons' shan't hunt humans either. This world we live in shall be divided between both.".

A proposal —otherwise known as The Promise— was formed by the first head of the Ratri family. It declared that "humans and demons are restricted from further hunting." Afterwards, the world was broken into two — one side belonging to the demons while the other belonging to the humans.

Birth of a Religion: Heathen
Some demons did not approve of this deal and thus refused to even nibble any of the children born in the farms. This caused these demons to be branded as "heathens" and were shunned for their behavior. However, while their religion prohibits them from eating humans born in the farms, they wait for The Promise to be broken and be able to hunt humans again.}}

Anemone Plants
The Anemone plant is a large, bulbous plant that, when broken open, contains fresh, drinkable water. Its species name is unknown, but as their Adventures of Ugo counterpart is described as an anemone, they are often referred to as such.

Jewel Flowers
Described as jewels in The Adventures of Ugo, these flowers give off a beautiful glow admired by the children. They are often seen used in demons' lanterns, and grow rather plentifully throughout the demon world.

Monkeys
Monkeys are found in a forest encountered by the B06-32 refugees on their way away from the blown up shelter. Their appearance most closely resembles real-life Squirrel Monkeys, though their exact species is unknown.

Crawling Fish
Crawling fishlike creatures are seen in the caverns beneath the Bloodsucker Trees.

Horses
Numerous horses are seen throughout the series, generally used by humans in the demon world.

Flying Newts
Newt-shaped creatures with insectoid wings are frequently seen flying around in various parts of the demon world.

Sleipnir
The demonic variant of horses, ridden by Mujika.

Large Insect
A swarm of unspecified large horned insects appears in caverns beneath the Bloodsucker Trees.

Butterflies
A butterfly is seen flying near Mujika in one scene.

Canine Creature
An unknown wolflike creature is seen mummified by the Bloodsucker Trees.

Candle Trees
In the Goldy Pond arc, Yugo leads Emma and Ray through a forest of these trees. They are described as feeling as though they are made of stone and looking like melting candles. Various vines and lichens grow on them.

Demon Forest
A vast area of dense trees and wildlife located outside the human plantations, it contains a variety of bizarre fauna and plants.

Grace Field House
One of four farms where the human children left behind by their ancestors are raised as livestock by former livestock known as "Mamas" and are branded with tattoos and shipped out at certain ages to become offerings to an unknown demon lord. It was set on fire by the children from ages 5-12 who escaped to the demon world after discovering its true purpose. After having burned down to the ground, the children were moved over to a different part of the plantation under a new mama.

Glory Bell
A separate plantation where livestock tattoos are determined by a combination of letters and numbers. A group of kids escaped from there and were journeying to Minerva's second shelter at Goldy Pond before they were captured by Poachers and all killed, other than Mister and Lucas.

Grand Valley
Another premium plantation farm where children are being raised to serve as livestock for the demons. In this farm, children are being prepared to be shipped out to Goldy Pond because Grand Duke Leuvis serves as a purveyor so he has a lot of power both in Goldy Pond and Grand Valley. All members of the Goldy Pond Resistance movement and the likes of Theo, Monica, and Jake came from this orphanage.

Factory Farms
Factory Farms are hundreds of farms that contain cheap meat for the demon population. The children in these farms have no free will of their own or any power of speech, as they are only kept barely alive and spend all of their lives being fattened up by the demons to be eaten by them. One of the children living in Goldy Pond, Adam, came from a Factory Farm.

Shelter B06-32
Shelter B06-32 was Minerva's first hideout and was set up as both an armory, a source of knowledge about the world's affairs, and a safe haven for escapees who possessed promised pens and were smart enough to escape the plantations.

Goldy Pond
While Shelter B06-32 was only a temporary hideout for escapees to meet with Minerva and regroup, Goldy Pond was his actual base of operations. It contained a small village that served as a front for the true entrance, hidden under a silo and several ladders underground lies a floating island, which contains an elevator to the human world when a promised pen is inserted into it.

Cuvitidala
The ancient ruins of Cuvitidala are the central focus and namesake of the Cuvitidala Arc. It is implied that the place was once a sacred shrine, but its use has been long since discontinued. As it has been closed down, only Emma, having the eye amulet, can use the shrine's clairvoyant abilities.

Trivia

 * The demon world is theoretically divided into four areas, as per Minerva's pen, with Grace Field House as the origin point. Going clockwise, they are labeled A, B, C, and D.