But the Reapers, Players, Noise, and any other beings in the UG can be seen from the UG because they are
in the UG. And it wouldn't make sense for them to be lower, I'm pretty sure the Secret Reports state that the RG is the lowest of the realms, and personally, and as far as can be observed so far, the higher up someone goes throughout the planes, the more amazing things can happen. Eg: RG, normal world. Noise plane, wierd animals. UG, magical pins and all that jazz. Angel's plane, are said to be travellers, possibly over great distances, possibly extremely quickly and/or through unusual means.
And I realised something, for each plane, at the lowest point of its heirarchy, is an area that that portion of the realm has control over. EG = The smaller portions of Higher Planes cover larger areas.
The whole world is present through all planes (as far as we can tell). The RG is compartmentalised into areas the size of suburbs, or wards (for us in Melbourne) taking up several suburbs, but not larger than a city. Move up to the UG, and you've got entire cities under a heirarchy, and remember, or at least in the example of Shibuya, travel to adjacent Underground Cities was impossible. Move up to a higher plane still, possibly the Reaper's Native plane, and you'd have countries. Angels, the whole world. Steps up through the planes allow for greater sized areas to be controlled by the lowest point in that planes heirarchy.
Please don't do something that'll make we quote every single Secret Report and discern every detail into truths, speculations, and hypotheses, it's very tempting for me to do so.
Edit: Something I noticed:
Secret Report 1 said:
However, this particular Game is saddled with a nigh-unbelievable set of extenuating circumstances, catching the attention of the Higher Plane. Thus, I shall be taking a more hands-on role this time, as detailed in this report.
Depending on how you want to interpret this, The Producer could be talking about just another game, a prior one, or he could mean with 'this time' as another Game with rather extreme differences to previous ones.