To get to the Tatami Room you have to go to Heart World -> The Deciding Street -> Netherworld. In the Nether world you have to go over the big bridge to where the 4 rooms are. The room that has been empty before now has a small hole in the wall on the right. Again, you have to be small to get in, so you need the child or fairy effect to get in or out. Behind the cupboard you can find some money. Was that there before?
I'm glad that the new area is a bit smaller than the new wataru maps. In a gap between two buildings there is also a bit of money and far to the left, where the BGM fades, is a stereo that plays another BGM and can be switched on of off. But I don't really know how to call the area. Maybe something like Police District or Street Basketball Area. We can wait for a few other suggestions.