I tried this half Japanese girl (she's half Chinese, half Japanese) as well, really bad experience.
And this walk-up girl is exactly the same person:
http://go141.com/zh/A44521-尖沙咀-美少女-JapaneseH.html?ref=Search(nationality,region)
But instead of HKD1000 at Champagne, the same girl will charge you HKD2500 at an hourly hotel not far from Champagne, for the same bad service.