This is just a hunch I have, but I bet that there are 4 different “continuities” total.
Let’s call them A, B, C, and D. Each of these continuities overlaps with two other ones in some way. So, B overlaps with A and C, C overlaps with B and D, etc…
Then there’s the room itself which overlaps with all 4 continuities. Let’s call that “E”.
To draw a picture:
AAB
DEB
DCC… I could be wrong.

This is the picture that Quarkboy meant. The picture was taken from the second episode: it was the penultimate film made by Watashi and the last film that was not meant to offend. The center square is connected to all of the other four tatami. It is the 'E' continuity in Quarkboy's example.
Yojo-han Shinwa Taikei is transliterated into English as the Four-and-a-Half Tatami Myth Compendium. It is translated as The Tatami Galaxy in English. I was reading all the posts of the two forums that I visit regarding The Tatami Galaxy, and it was the post that gave me pause and made me think about its implications. One has already seen the intersect clearly and explicitly shown in the fifth episode: there is at least a parallel universe that is happening within the show, and the crossing over of the older Watashi simply proves that. The different universes intertwine in different ways: they are somehow interconnected, like different planetary systems are, into a galaxy. Read the rest of this entry ยป