Sakurai’s Daily Screenshot - July 24, 2014
"This is the Tomodachi Life stage that’s exclusive to the 3DS version! The front walls of the apartments disappear so you can see the area within when a fighter overlaps with the room. The rooms are randomly placed and selected from among several types. Planting an X Bomb behind a wall might be an effective tactic.
You might run into a Mii living in the room! The Mii characters are taken from the data in your 3DS system, so you could find your friends living in the apartments.” - Masahiro Sakurai