MG Setting

Realms: The Realms take the form of various mythologies, folk legends, and other beliefs held by humans over the course of their history. Disconnected from the Human World, now their inhabitants seek to create Contracts with Humans through the use of Desires, or wishes that those still not completely disconnected from the Realms. The inhabitants of the Realms are not completely good nor are they completely evil, but somewhere in between.
Realm Magic: After a Magical Girl has made a Contract with a inhabitant of one of the Realms through use of their Desire, they are given power over the Source of the Realm, whatever it may be. This magic draws its power from the energies associated with that Patron's Realm and in turn grants the Magical Girl that power. Realm Magic is usually just the enforcement of that associated Realm's rules and laws onto the Human World. However, due to the Boundary around the Human World as a result of Origin Magic, Patrons can only enter into the Human World through weak points in the Boundary. It is through these weak points that energies of the Realms leak out into the Human World, sometimes causing monsters as well.
Patrons: Inhabitants of the Realms that, for one reason or another, make Contracts with Humans in order to grant them power through a Desire and create a Magical Girl. Usually, girls are chosen to become Magical Girls over boys due to their greater tendency for emotional outbursts over boys, though their male counterparts are definitely acceptable replacements if a Patron cannot find a girl.
The Divide: An ancient event that rended the Human World from the Realms, forever separating the two between the Boundary, the in-between space between both. In small gaps between the Boundary, even now, one can find the influence and realities of the Realms seep through, effecting the Human World on the other side as Patrons and monsters find their way into our world.
Dark Magical Girls: Sometimes, for whatever reason, a Patron finds an acceptable Magical Girl to accept a Contract and allows them to sink into their more base Desires, creating a Dark Magical Girl. These Magical Girls, instead of accepting power that is for the purpose of more selfless Desires, instead indulge themselves. Dark Magical Girls are usually found where the Boundary is weak, thus creating more disruptions in the natural laws of the Human World due to the use of Realm Magic.
Boundary Magic: Created as a by-product of the Boundary and the severing of the Realms and the Human World, Human Magic, instead of drawing from a Source like is the case in Realm Magic, instead draws from the natural Belief and the Magical Girl's personal experience in the world. Similar to how Realm Magic enforces the laws and rules of its particular Realm, Human Magic instead enforces the natural laws of the Human World, inducing an anti-magic effect on those effected. It is for this reason that Adults cannot see or perceive the existence of Magical Girls, Patrons, and the Realms, since the longer one lives in the Human World, the more attuned they become to Human Magic. This power only becomes stronger with age, though due to the passive effect of it, most Humans barely recognize it in their lifetime.
Origin Magic: Instead of manipulating the Perception of Reality like Human Magic or Realm Magic, Origin Magic uses the powers of Borders, Boundaries, and Barriers to influence the world. It was in this way that the Boundary was created around the Human World, preventing the Realms from interacting directly with the Human World. Origin Magic, in this way, relies upon the Potential of the user, the countless possibilities that they hold to either seal off or move across boundaries. However, due to the power of this type of Magic, the knowledge of it has been lost to the ages.