Realm of Demons

The realm of demons is the realm of reality that Demons reside. The demonic realm is toxic to humans as the air possessed O3 (ozone) instead of O2 (dioxide). While the demon body is capable of breaking ozone into oxygen, the human body will eventually suffer from suffocation, as well as extreme lung damage. There are 4 realms that make up the demonic realm, three are hubs for the different kinds of demons, along with one main realm. Regardless, the demonic realm is in an eternal state of dusk.

The Realm of Spirit Demons
Spirit demons are spirits who have become corrupted over time with negative emotions to the point of becoming a demon. Spirits of magical entities such as witches and half-demons are unable to become Spirit Demons. Having once lived, becoming a spirit and becoming corrupt by their own mind, Spirit demons often haunt the mortal realm. Their realm is similar to both the realm of Spirits and the Realm of the living but a lot more 'abandoned'. These demons retain their intangibility, however, that can regain their tangibility at the temporary cost of their intangibility (if they are hunting someone, they become solid in order to hurt them/interact with things, leaving a window of time where they can be hurt and killed/sent back, when in 'spirit' form, they escape the dangers of threats by becoming untouchable but they can't touch anything either). Some examples are the Onryo, Ubume, Funayurei, Teke-teke, and Zashiki-warashi. While not all are malicious or dangerous such as the child-fond Ubume, many are.

There are two kinds of spirit demons, spirits that went mad and became demons or spirits that got stuck to something and became a demon over time. While object themselves can gain sentience after existing long enough, spirits that end up stuck to something will simply just possess that item (in most cases, in one way or another they possess the thing that killed them) and eventually become a pure demon as a result, the new found consciousness of the item merging with that of the spirit. These types of spirits are known as tsukumogami, and while there are often not demons, they sure are on their way of eventually becoming one. Tsukumogami are likely to be found in the realm of the living but they are often cast into the demon realm if discovered in the Spirit Realm.

The Realm of Counter Demons
Counter Demons are demon versions of humans. In ancient times, they would be born when humans looked at their reflection for the first time. In modern times, all humans and half-demons have a counter demon, born when they are, while witches and warlocks do not. Unlike other demons, Counter Demons are linked to whoever is their original and will die when they do. Their realm is just like the Realm of the Living but more destroyed. Since their mortality is tied to their human counterpart, these demons are far more violent as they have the brain of a human but they act out on the darker desires that humans often don't. While there are counter demons who are not violent, these counter demons are mocked for their pacifism. These demons are unable to leave the demon realm, with the sole exception of curses that bind them into the same body as their human counterpart.

The Realm of Pure Demons
Pure demons are born from magic. Unlike the other kinds of demons, they generally have no sense of mortality, as they do not eventually die like Counter Demons, and most of them are not derived from the living like Spirit demons. People that die and directly become demons instead of a spirit, or demon half breeds that become demons upon their deaths instead of spirits, become pure demons. Things that aged to a certain point can also become demons. Some examples include Nekomata, Kitsune, and Tsukumogami.