Karaoke places also called KTV can be found almost everywhere in China's main cities.
As they can be sometimes a popular place of pure and harmless entertainment to only sing and drink for the young and older chinese people, a lot of those places are also a cover for prostitution where young and less young hostesses work.
Having been usually trafficked from poorer provinces like Sichuan,Yunnan or Henan, those girls work days and nights to keep company to male clients and also provide sexual favours.
Prostitution is illegal in China.