im slow af and i just finished it and, is the show non linear? and maru is tokio's child?
There's actually two lines in that show, One is Maru and Kiriko's journey, and the other is the children kept in the shelter, which is actually past tense.
Later Maru and Kiriko encounter with Usami Shun, who is a doctor but also the kid who escaped from that shelter with Mimihime. And he was actually trying to save Mimihime from the disease in the present time. After you see that you should understand that the children facility kinda thing is actually happened in the past and Maru and Kiriko tries to find that place in the present time