"And your job is... getting people to make wishes and become magical girls?"

That's right.

"What would happen if nobody killed the witches?"

Witches are very dangerous. When they grow, they can sometimes threaten whole human cities. So far they have never gotten very much bigger than that, because magical girls hunt them.

"...What do they do to whole human cities?"

This can depend on the witch, but sometimes the destruction is blamed on a natural disaster, if the witch is large enough. Ordinary humans can't see the witches.

"But we're not ordinary?"

You aren't! You both have the potential to make a contract with me and become magical girls. That's also why you can see me.

"...We couldn't otherwise? Why not?"

If normal humans could see me it would cause a lot of problems.

"We've never seen you before."

I'm very small, and because of telepathy, I don't need to be near another person to talk to them, it explains.

"And I bet Ghys didn't want you talking to me until she decided whether to introduce us... could I resurrect Stasya Koskin with a wish? I'm not sure if I want to, but could I?"

Yes, you have enough potential to bring her back to life if that is what you wish.

"Good to know, I guess."

"Could she - or I, which of us has more oomph? - bring back multiple people, and if so, how many?"

Solvei has more potential than you, but either of you could bring back just one person, says Kyubey.

Kyubey hops in and lands in Solvei's lap and curls up there, fluffily.

I think it is all the fur, says Kyubey.

"The tiny paws are also a contributing factor."

You are very likely right, agrees Kyubey.

"So, regarding people with magic powers. It sounds like a good deal all by itself, but you're calling it a contract and adding wishes on top of the bargain."