So, then, this is a continuation of last chapter's "side character wrapping-up" theme. The main difference being that Mako didn't leave as the other two did. Hopefully, she'll make an appearance again before this series ends.
Noo!! That's quite a sad revelation especially if she's actually Mako from Children don't play in the dark. You could tell she was very close with her bro and in that other manga the bro was very protective of her because of her powers even in death it seems. Hope she's gonna survive somehow as the whole thing is setting up to be an end of the world scenario or at least regain back her powers or see her bro again.