Why's it spreading now all of a sudden?

That, we don't know.

We discovered the situation when a patient was brought to us late last night.

Even though Master's taking care of him, he hasn't been in talking condition quite yet.

Apparently he's a carpenter, so that's our lead to find the first people to vaccinate.

Our first priority is to stop it from spreading any further.

Hmm. A carpenter.

You don't say...

In that case, the cause seems pretty obvious.

Wait, what? Do you know something?

Yeah.

Disease. Construction. Youkai.

Add those together, and what do you get?

Okay, I get you.

In other words, Marisa...