@midarmour Yeah, full-contact karate people have used it, kickboxers have used it, Nak Muays have used it.
I'm surprised that no Nak Muays have turned up so far, maybe the author is saving them for later.
Also I agree that the upper body shot confuses me as well. It's possible it's a translation of chudan, which is a straight punch aimed at the solar plexus. But as you said it doesn't quite look like she does a full on karate punch, unless the author drew in the step-in and the punch sequentially which is not how you're supposed to do it.