This one is a new stage to me as I didn’t have the 3DS version of Smash 4. It’s based on the game Tomodachi Life for 3DS. I never played it, but it seemed like it was a kind of like Animal Crossing or the Sims but heavily relied on the use of Miis.
The stage is pretty much a medium-sized apartment building. Once you get close you can see different rooms. The stage will actually put your own Miis in the stage. The rooms are very good about hiding items when nobody is there.
But the bravest folks usually battle up on the rooftop.
While far from my favorite stage, I do like it.