The Nothingness
The Nothingness is the plane of existence in which Stories exist. As the name implies, it is effectively empty besides the Stories, and a few "out of space" locations, most of which are inhabited by certain beings specific to the Storyverse.
There are other planes 'above' and 'below' the Nothingness, but they are incredibly hard to access for anyone who's not incredibly powerful. Even most deity species don't have the power to move in those ways. Also, despite the description of being 'above' and 'below', they are not necessarily accessibly by going downward or upward.
Doña Sapphira has organized the Janitor Menagerie into what she calls "office spaces". These are all office-themed Miranim who act as bases and office locations for the Menagerie and its employees.