But then the girl steps like she's starting to dance - and sparkles appear in the air around her!  Her pants billow out into a poofy dress, and a sword appears in her hand out of nowhere - and she vaults onto the roof of the school and vanishes!

Lila stares.

There's no way she could have hidden that dress or that sword anywhere.

Something interesting is happening!  Can magic be real after all?

But how can she join in the story?  She didn't see the magical girl's face - and (she stumbles back) she can't see her on the roof of the school anymore -

The young student who just turned the corner doesn't not lock eyes with the young woman she sees also boggling at the roof.  "...Did you just see someone absolutely trounce the standing-start high jump record while wearing a poofy skirt and holding a sword?  I need to know if I need to deal with having some sort of mental break in the past thirty seconds.  Though I'm pretty sure I'm not experiencing the - odd alterations to salience - that I would think might also appear with a hallucination, and you're looking for - whatever that was - too..."

Lila whirls, only to see another student in perfectly normal clothes with absolutely no magic visible.  Unfortunately.

Well, she's involved with the magic too now!

"Yes - and the sword and skirt appeared out of nowhere while I was watching her!  Complete with sparkles and... maybe ribbons?... and I was boggling too much to even ask her what was going on or who she is!"

"One presumably would!  ...Why the heck, if the existence of magical girls or what-have-you is not common knowledge -

"Why did we see her?  Am I going to have to watch out for some sort of - antimemetics task force trying to break into my house to keep the Masquerade up?  I do not like that idea..."

"I don't know!  But I hope someone shows up so I can find out what's going on!"

So I can be a magical girl too, she doesn't say.  She's suddenly hoping for that too much to say it out loud and have it dashed.

"... though yeah, if there's a Masquerade, maybe I shouldn't go telling just everyone... there has to be some reason we don't all know about them already, but..."

"For all we know, it's a really dumb one like 'hiding is traditional' - would you recognize the student if you saw them again, maybe we could ask them -"

"I - I caught a glimpse of her face while she was jumping, but maybe the magic changed her face too not just her clothes?  And I didn't recognize her; I don't know if she's even a student - this's a big school, but if they're hiding, maybe there's a secret Hogwarts next door?"

Speaking about names and faces - "You're Diana, right?  I think I remember you from English.  Lila."  She sticks out her hand.

"I - yes - good to meet you - again?"

She...shakes it!

"So unless we see her again, we need to track down clues some other way...  I wish I'd gotten a picture.  I've already looked for any traces of magic, so just looking again won't do any good... unless maybe it was there all along and we can suddenly see through hiding-spells now for some reason?  Do you have any other ideas?  I guess I could always run over to the buses and start yelling about magic?"

"Too likely to backfire, in my opinion.  You don't want a crackpot reputation; even if you find proof afterwards you'll be dismissed.  That would suck."

"Plus your Masquerade enforcers.  In fact..."

She sets down her backpack, pulls out her math notebook, and writes on the next page (angling it so Diana can read):  "Saw Real Magic.  Girl conjured a sword and jumped to the roof of the school.  Diana from English saw her too.  Going to try to find out how to be a magic girl too!"

A - creature that is definitely not a cat - lands on the page before she gets too far into it.

:I would prefer,: it thinks at her, :that you didn't finish writing that.  On the other appendage, if you wish to find out how to become a magical girl...All you need to do is ask me.:

Lila starts and almost drops her notebook.  "Yes!  Tell me how!"

A moment later, she looks over at Diana - "Did you hear that?  It said to ask it how to become a magical girl!"

:If you make a contract with me, you can become a magical girl!  I did not say that.:

Diana squints at the not-cat suspiciously.

"And what do you get out of it?  Power never comes free around here."

:It is in our interests to ensure the continued existence of the universe, no matter the cost, Diana Adelene Vitalis.  You surely know this.:

"...Then how the fuck does this lead to that?"

The creature that continues to be not a cat curls up on Lila's notebook, now that that surface is less unsteady from surprise.

(Being thrown about would damage its dignity, which it needs in order to bring this conversation to a preferable end.)

:The process of creating magical girls has results that are ultimately negentropic, despite the significant startup costs.:

A bit of suspicion has leavened Lila’s eagerness ever since the word “contract.”  She has heard the fairy-tales about Fay bargains.

At least entropy gives an explanation… at least for the “why” part.

“What would I be contracting to do?  As Dad says, nothing we do can really reduce entropy… at least without magic?”

:You would, in exchange for the otherwise unrealizeable potential energy of your soul, receive one "wish" in proportion to said potential.  Wishes are determined primarily by the intent of the bearer, but may be shaped by the words they choose to form them into things that are less satisfying - this, I tell you because buyer's remorse is not in my interests.:

Because magical girls produce more power, on net, if they do not immediately witch out.  Though of course, it is not actually saying that, or in any way acting to reveal it.

:No other obligations exist in the contract.:

"I'm giving you the energy of my soul?  What does that mean for me?"

That... doesn't sound not like a Fay bargain.

:My apologies; the prior communication was unacceptably imprecise.  In exchange for my assistance in assembling the necessary structures for converting that potential into useable energy.:

Being able to use up the energy of her soul still sounds like it might be bad... but on the other hand, magic!  And a Wish!

"And then... we get other magic?  Or was that other girl's wish to have magic swords and dresses and jumping?"

(She wouldn't dislike wishing for that, but... there could be more.)

:That was not her wish, no.  Transforming, and summoning a personal item that is usually a weapon, are inherent functions of being a magical girl.  Enhancing physical force is often a learned technique, as it was in this particular case.: