Inspired by the popular anime Sailor Moon and its Moon Kingdom, the Moon Palace is a fictional location on Earth's Moon powered by magic. It exists within a magical bubble that contains and maintains life. It is the residence of the Moon Monarch Mavis DeLuna, crowned by divine right by the goddess Selene, and their chosen Lunar Guardians.
Mavis (often referred to as "Their Majesty") and the Lunar Guardians permanently live here, with the palace's magic connecting them to other worlds they've visited and/or protected. It also serves as a base, being the closest location to protect planet Earth and its surrounding galaxy. People and creatures displaced or seeking refuge from their worlds often visit or reside here.
Despite being a Monarch, Mavis does her best to stay humble and grounded; she rules the Moon Palace with benevolence and kindness. The palace has many amenities and is luxurious and grand, so that its residents and the Monarch within it live in comfort and stability. Some people stay temporarily, then move on when they are ready; others decide to make the palace their permanent home, to escape lives of stress or strife and find lasting peace.
Able-bodied residents are requested to help maintain the palace and its amenities at least once while they stay. In return they are given free room and board, and extracurricular activities to be pursued at their leisure. Residents of the Moon Palace are never left going without; it acts as a safe haven, almost a small utopia. However, it is not without flaws, and must be protected from outside sources that seek to shatter its protective bubble and disrupt the peace.
In addition to the palace residents, large numbers of Clefairy (from the anime and popular video game series Pokémon) and its evolutions reside on the Moon, and have also integrated into the palace's peaceful life. In its source material, Clefairy are rumored to be extraterrestrial creatures hailing from the Moon itself.