@NoraDaimio I just feel there are a lot of things that make more sense if they were going on at different times.
Since the goal of the school seems to be creating super soldiers for outside groups, the implication is that wars are still happening. Given the state of society, it doesn’t make sense to (1) have wars in the first place and (2) require that level of technology to win.
Furthermore, the people who will be using these kids seem to some sort of foreign power (i.e. they need a translator). If that’s the case, how do they even have the capacity to communicate and travel to Japan (if the school is even located there)? At one point, Kiruko mentions that airplanes are no longer functional. I can’t imagine they are doing it by boat. If they have the technology to create energy weapons, I don’t see a reason why they wouldn’t make planes especially since they are at war.
The only way the whole super soldier thing would make sense is that either the two stories happening at a different times, or that there are still significant parts of the world that have maintained some high level of technology while Japan is in ruins.
Another thing that suggests at least some time difference is the whole deal with Maru’s first escort, Mikura. She knows that Tokio has the disease and has a cure for it. How did she know that and how would she have possession have the cure before the school even was aware of it? Based on current events, the school administrators had no clue about the cores. They freaked out when they saw the core from the dead classmate. You would assume they would have some idea of what was but they had no idea what it was when they saw it.
If things were happening concurrently, Mikura already having the cure before meeting Maru means that someone would had to have known that students were going to develop this disease. Now, that’s certainly possible, but it seems more likely that Mikura was sent on her journey after that became a problem. In my opinion there’s a few months of a gap, at the bare minimum, between the two stories.
Also, regarding Kona’s visions. He calls the people who will take Tokio the same people who took his friend, Asura. It’s not clear to me how that’s related to our intrepid duo so his vision might be related to something entirely separate.