Been keeping up with the weekly anime but I've been thinking a lot about heavenly delusion. I have a theory for how a lot of things connect.
I think that the heaven segments are 18-19 years before the parts with maru and kiruko and that maru is tokio's son. I also don't think he can use "maru touch" on humans, but that both the girl from episode 8 and the king of hotels are from heaven and part maneater. I suspect Dr. Usami was from heaven (part of why he had advanced electronic know how AND generators and the coin with their logo.
I believe the collapse was caused by heaven trying to engineer humanlike lifeforms capable of surviving some disease or possibly just improving on humanity, since each one has different powers. One of them, ends up going haywire and creating many of the maneaters we see post collapse, including the fish with arms that the one kid drew. I'm still not sure exactly who will be the one to go out of control. It's possible it'll be the guy that drew them, tokio, the black organ left over from the sick kid, or mimihime. I'm kind of leaning towards mimihime. I suspect the AI running the facility wanted this outcome and caused it to happen. Then again, the humans in the facility refer to some destined time and all they do is for that time at which point they will no longer be able to help. Perhaps that time is the collapse.
I haven't put so much thought into a series in quite a while and it's great.