So... it seems her powers work if her underwear is removed at all? As far as I can tell, she didn't intentionally remove her bra; it came apart because she jerked her arms after being stabbed with the pin. (Incidentally, how bad is that employee if she can't hem a pant leg without stabbing the wearer...) So I guess this would mean that her underwear just needs to come off, regardless of how.
Also, nice surprise attack from Shirota at the end!