Note: For the sake of ease and consistence, the locations of all things will be told from the perspective of someone exiting Ai's home through the front door.
The realm of eternal twilight is a place that has been implied to be separate from the normal world. The name has been derived from the fact that the time of the day in this realm is always twilight. The skies are mainly golden, with bits of blue, as it usually is in the earliest hours of twilight known as the golden hour. It is in this realm that Ai resides.
The realm also has other mysterious characteristics other than its eternal twilight. One such characteristic is that one ends up in the same place they start walking from even if they move in one direction, as Hotaru Meshiai has been shown to start walking from Ai's home and ending up there again. On the same observation, it is also shown that the realm is very limited in space, as Hotaru walked the whole distance of the realm in just a while.
The only people who has been shown to be able to enter and exit the realm on their own are Ai, Kikuri, and Ai's companions. However, the only people who seemingly have the ability to bring others in and out of the realm are limited to Ai, Kikuri, and Ai's grandmother.
The realm is abundant in trees, flowers, and even crops, but any other living being other than the plant life here is rare. The only humans known to inhabit this place are Ai, her grandmother, and the companions of Ai. The only other living being that has been shown to exist is a single ladybird beetle. The master of hell also frequently visits the realm in the form of a small three-eyed spider.
The sun is always at the upper-front of the house. Even though there are lots of trees in this place, there is a lone tree right in the front of the house which is noteworthy, as there is a statue of Ojizō-Sama under it. Another notable thing is that clusters of Higanbana flowers grow in the garden all around the house.
Another noteworthy lone tree is situated somewhere in the realm. When somebody accesses the Jigoku Tsūshin, Ai brings them to this realm right under or near this tree. This is also usually the only way for normal people to get to this realm.
Notable normal people who have visited this realm include Hajime Shibata, who had been forcefully brought in the realm by Ai, and Hotaru Meshiai, who had been forcefully brought in the realm by Kikuri. Since only Ai, Kikuri, and Ai's grandmother can bring someone in and out of the realm, both Hajime and Hotaru had been trapped for a while in the realm, until the former had been released by Ai's grandmother, and the latter had been released by Ai herself.
On the right side of the house is a separate wooden room with a good distance between it and the house. It also has vent-like spacing at the top of each wall. It seems to have the capacity to hold only one person comfortably. The purpose of this room is unknown.
On the back of the house is a stream of water. There are some small wooden stairs at the bank of the stream, attached to a small wooden pier. The stream also has occasional large rocks. It is in this stream that Ai always washes herself as a ritualistic purification process before setting out to take someone to hell.
No other houses surround Ai's home, as it is the only house in the realm. The house itself is a traditional old-fashioned cottage with a thatched roof. It has two doors - one in the front, and another at the back leading directly to the pier mentioned earlier. Both these doors have an opening on their upper side, with bars of wood. It also has a window on the left side of the front door.
From the inside, the house looks old and traditional. The insides are mainly made from wood, bamboo, or straw, and the floor is floored with tatami. Near the front door on the left, there are two shelves, one being over another, with some small pots placed on them.
There are also a few large pots kept on the left under the shelves. The largest one of these pots is the most noteworthy, as inside it is a mysteriously huge amount of space. The place inside this pot carries all the burning candles with the names of the people who have taken Ai's service, and is bound by her contract to go to hell after they die. Almost all of these candles are floating.
On the right further inside, there is a shōji door, leading to another small room, inside which lives Ai's grandmother. It is also worth mentioning that the wall of Ai's grandmother's room that is visible outside the house is also made from shōji. Neither the inside of the room, nor has Ai's grandmother ever been shown. Only the silhouette of Ai's grandmother, and a spinning wheel that Ai's grandmother always spins is shown from the other side of the shōji. Only a few people have seen the room and Ai's grandmother, and they include Ai, Kikuri, Hotaru, and presumably Hajime Shibata.
Back on the first room, in the left corner of the room further inside is a set of wooden drawers. Right beside it is a small, low-lying wooden table, with a vase with some flowers on the left, and a computer on the right. This computer is markedly incongruous with the rest of the decor, and is seemingly of the oldest models of personal computer ever made. It also has an Internet connection, and its primary purpose is to serve the Jigoku Tsūshin website, and receive requests from clients that are willing to take Ai's service.
- Some places in the realm of eternal twilight, including near and inside Ai's house, has changed some elements from the first season in the second season.