
Toriyama's diagram of the cosmos was mainly made to assist the anime staff with worldbuilding and conceptualising where everything is in relation to each other in the Dragon World, but it has appeared in a few stories. Most notably, Dai Kaio forms a miniature replica of it on his fingertip in the Z anime, and the Super manga briefly shows Universe 10 as having an identical appearance to Universe 7, seemingly confirming that all universes have the same basic structure.
Personally, I always perceived the map as being more of a symbolic, non-literal imagining of how the universe roughly looks, simplified for our mortal eyes. Kinda like how ancient cartographers took liberties with map designs of the Seven Seas, or how Renaissance artists symbolically represented Heaven and Hell as these layered planes of existence. You see in work based on Dante's Divine Comedy, Hell is depicted as like a narrowing funnel stretching out below the living world. So I'd consider the possibility that the living realm of Universe 7 isn't literally surrounded by a brick wall, but the design decision was made to symbolise that it is a grounded, physical place below the ethereal planes of reality.
I understand though that the Kanzenshuu guides and eventual wiki can only go off official sources, so there's little room for this kind of speculation. This isn't me saying that it's wrong or anything, I'm just spitballing ideas. As always, thanks for the hard work put into the site!



