From Black Lagoon. Cosplayer is Omi K. Gibson.
Also known as Sawyer the Cleaner, is a young girl, appearing to be in her late teens-early twenties, who specializes in body disposal, but also does occasional bounty hunter work. Sawyer is the person that the Triads (and probably others) turn to for executing people in the most brutal ways possible, usually to serve as examples for their clientele and enemies. Her legitimate business front is, fittingly, a meat packing business named "U.G. Pork". Sawyer works in a white-tiled room which is covered in blood from her various executions, and uses a chainsaw as her tool of trade. When on the job, she is dressed like a surgeon, but otherwise she wears gothic clothing. Few people seem to recognize her when she is not wearing her surgeon's robes because when she's on the job she wears a mask and goggles. Because her throat had been cut open at some point, she speaks with an Ultravoice. She also seems to have various emotional issues, as she will drop into fetal position if she loses her Ultravoice. (lagooncompany.wikia.com)