[Harley's kill count is definitely high at this point - she'd taken out over 50 soldiers in one sitting once, escaping from interrogation on Corto Maltese, and that was just the one time. She doesn't seem to show an ounce of regret or second thoughts about killing the Sylphid, hadn't about any of them. They're the mission, they're in the way, they're the bad guys. That makes them targets, and targets are for shooting.

So she looks utterly unbothered as she trots back over to Mikumo and tells her how cool she looked using her power.]

Ohhh, is that your Heba thingy? Mine is weapons. I can just pull 'em out of nowhere, they're just...there. Y'know?

[How would she know, Harley?]

Water bottle's a good idea. You could get one'a those canteens you stick on your belt or somethin'!