Jira? Yeah, she could be in an ops suit too, but I think Kaya is a real tough cookie, much more than she lets on. I think that if we haven't seen any particular combat skills or other physical abilities (apart from her gorgeous body and beautiful tattoos), it's simply because she hasn't needed to use them so far. Being a very smart girl, she knows how to play the right card at the right time. She's at least as smart as the MC, so I'm sure she'd come up with a satisfactory excuse for the principal or her lapdog Harada. What's more, we can assume that her outfit includes a mask or some other form of covering so she won't risk being recognized.
But Jira is qualified and trained for this job, and her mysterious client watching the MC from afar through Jira's eyes leaves many doubts, depending on who he/she is.