Her name is Li Chang Ge. From this manga, unfortunately it had licencing issues and will likely never be completed, but hot damn its good. http://mangafox.la/manga/chang_ge_xing/v02/c005/13.html
Yeah its from this manga: http://mangafox.la/manga/chang_ge_xing/v02/c005/13.html and as you can see it's just a threat haha My holy grail of manga; storyline, characters, art, got it all.
Yeah, I can already tell I'd really like the MC (assuming that's her). Sadly, it doesn't look like it's being translated.