Apartment owners can design their apartments using furniture items (some usable) according to their preferences. Once saved, they can visit these designs as well as invite other players to their apartments to hang out and/or host events.
In order to edit an apartment, the player needs to have its ownership, and then go to the Apartments Complex (in front of central park) in Yorokobi Town or Isogashi City. Interact with the receptionist and choose their apartment then select edit button.
This should open up the apartment editor for that specific apartment.
Nomenclature
Rooms
Contrary to the name, rooms are not separate spaces, instead they allow the player to place a different set of wall design + floor design, creating a sense of a separate space within the same area.
All rooms need to be connected for the player to be able to save their design.
Large Items
Large items are furniture items that can be placed anywhere on the map. However, the player cannot place these items on top of another large item.
Players can also interact with certain large items to trigger certain functionality.
Small Items
Small items are furniture items that can be placed on large items as well as directly on the floor.
These usually cannot be interacted with.
Wall Items
Wall items are furniture items that can be placed on the wall.