It was a bit like that, but I don't think the affected area made much of a difference until the whole thing was gone, since the kids getting sent home were still "ill". [So they bounced back, but not just from leaving the area. Still, there's definitely a possibility of a connection there that they can't avoid looking into.

As for where they're working, Shun opens the front door set into the hill and leads her down the short entry hall, then off to the right, where there's a staircase down into the basement and a short, seemingly dead-end corridor with a door on both sides.

It's the corridor he takes, and opening either door reveals a small, somewhat disorganised library crammed with books. It's nothing like the scale or usefulness of the Heavens' one, but it also seems to be missing some of the chaff, having mostly mundane reference books that can be seen from here. On this side, at least.

There's some tables where they can set up, and Shun gives her the name as soon as she asks it. It's not uncommon, but also not common enough they should be getting a ridiculous amount of results back for it.]

Apparently the last principal died not long before the incident, and that was in April, so if it's further back than that it's probably to do with him.