Where exactly does the would-be assassin think he's going to run to? He's inside the tower, the belly of the proverbial beast. They can easily shut off teleportation between levels, locate him on any level, or even quickly guard the one and only exit. He has no chance of escape. It's quite...
To add to what @danberhe said. The short haired girl never speaks. Whenever she's in panel, it's always someone else speaking. She just seems to emote reactions.
Opinion to add as well, she looked way too calm during visible ghost activity. That's a ghost. Probably one of the bathroom Hanako.