More than the actual characterization itself, what hits me about this is the way she does the killing. I mean, normally in a manga, when you have people in a violent trade, they are hyperviolent--hard boiled, bigger than life, unstoppable killers with lightning speed and incredible accuracy. This is not actually that much more realistic, it seems like real hit men aren't nearly this smooth, even the high end ones--look at Mohamed Bone Sawman's boys. But still, it's a very different approach that gives much more attention to real world issues; she's pulling off the jobs in ways calculated to minimize complications, a hypercompetence much more grounded in the constraints of society.
The moment she offs someone quietly with no witnesses in a way that makes it look like an accident, rather than fighting her way past half a dozen bodyguards in a massive shootout, this tells us we are in a very different universe from that of most manga hit men.