Even after Fujiko had left the library earlier, Kotomi had stayed, picking out an inordinately large pile of books, finding a nice, empty aisle, and plopping herself down and reading without interruption.
When she heard someone new coming in, she considered simply picking up and leaving. She was in the process of staking up the books she hadn't finished yet, when she saw the older boy with purple eyes walk past the aisle she was sitting in, and sit in a chair that was within her field of view.
You're never going to get anywhere if you just run away from people.
"I'm afraid there's not much in these books about the facility," Kotomi said wearily. "Or much about our general situation either."