What is the Catalyst?

Talking with Yasurouka before the homeroom started clarified that she wasn't really pissed at me. Rather, I was confused about her reaction and the things that Kizhashi mentioned. All those things were implying towards a single possibility that was far from my reach at this point. Or this is what I thought then.

Yasurouka may have been interested in me lately, though knowing how her personality is, it could be a mere curiosity on her part. I would rather not arrive at any conclusions right now.

Homeroom was going on, and I was writing down some of the important things that Ms Tachibana was teaching us since our end semester exams were closing in on us, so it was time for me to get a bit serious and actually write down what was going on in the classes.

I noticed Tsumen was glancing at me. I slightly turned my head towards him without taking my eyes off the whiteboard and raised my eyebrows as a gesture to ask him, "what is it?"