She is sitting in the library, studying. It's her most common pastime, by hours; spending time with her sister is more enjoyable but Jaromira prefers to socialize more broadly and Katarzyna would only get in the way. This is better on net; the two of them share a room, so it isn't as though her sister's time is entirely hogged by the other girls who call this boarding school "home." Or at least "prison." Katarzyna doesn't mind it, though; the school library is excellent, and basic manners and care for the books has endeared her to the librarian to a sufficient degree to lubricate the interlibrary loans process when there's something she wants to read that they don't have.
"I suppose, but that introduces strictly more complexity than magical girls being a thing at all."
"True. I'm going to stop hypothesizing in the absence of fact, this can be a research project."
"Thank you, I will!"
"Anything fun in school or does it all pale in comparison to crackpot origin of magic theories?"
"I like my science class. And English makes Jaromira happy and I like seeing her happy."
"Are you allowed visitors on your campus? Should I come by sometime?"
"Yes, and certainly if you want to!"
"Are there specified times?"
"From after classes adjourn until curfew."
"Which is when?"
"Oh, right, sorry--three-ten to eight."
"Maybe I'll come by tomorrow. How do I find you?"
"My room number is 503. I'm usually either there or in the library."
Isabella writes the number on her hand.
Eee. "I can make you a map when we get back to the ground, if you want."
"On a related note, I thought of a less-low-hanging-fruit way of making money as a magical girl."
"What is it?"
"Large white petals with art on them."
"Ooh. You could also do, what's it called, scrimshaw!"
"--Oh, yes, excellent thought."
"It's probably being done but I haven't heard of it yet."
"Probably--for that matter, nacre jewelry."
"That I've heard of."