The Black Demons are the inhabitants of a world called "The Black Dimension", an inhospitable planet consisting of an immense desert and very few cities, with one big capital. The demons are divided into three classes by biological factors. The "tailed", called this way due to the long tail they have. They are the weakest, lacking any power and being comparable to normal humans, with the exception of few trained or gifted individuals like Khaled. Then comes the noble class, made up by artists, aristocrats or else. They have many powers, although this can vary from each person, and are often bored and spoiled, constantly searching for emotions, often at the expense of the lower class, considered like living junk. Due to their statuses and resources, they are the majority of the ones who escape from the Black Dimension. In the end there are the priests, the strongest demons, gifted with enormous powers that let them rule with the iron fist. This class, once governed the Black Dimension using the aforementioned powers, and methods like religion, racism and violence to oppress the population. One of the rights stripped from the citizens were that of travel between the worlds of the multiverse, with the death penalty for anyone that either comes to the Black Dimension or leaves and comes back. Ironically, the nobility and the priestly class were imprisoned by their own rules, some have settled, but others wanted freedom and have escaped illegally to other worlds.