Rather than saying there's no way that's her lunch, there's a rather easy solution for that.
Her backstory is a bit common, in a way, but with a different way to cope.
Can't even stand someone she likes and trusts.
"I'm beginning to feel like some villain, brainwashing a perfectly decent human..."
Well, he's a cat, so therefore a villain by default, though I'm not sure I'd call her a "perfectly decent human". Morally, maybe, but her sense...
So apparently the poor girl was beat as a child and would go to reciting math as a coping mechanism. That is bad and probably explains a lot about her social anxiety...
Yeah, that's about it. There's more to it regarding why she got beat up and why she uses math to cope, but suffice to say, she's met some bad people in her younger days.
Is brown haired guy on the cover the cat?
Nah, it's someone who hasn't appeared yet. Cat's black haired.