Li explained that Chinese and Vietnamese pimps control almost all of the women, with each taking care of four or five on average.
As 7 pm approached, the peak time for business on Vietnam Street, touts began to openly solicit customers. Prices averaged around 150 yuan for sex - the money is shared equally between the pimp, tout and prostitute - but competition can be fierce.
"Hey, come here," shouted two women at a man from their window. "Only 200 yuan and you can have both of us, 100 yuan for each. Very cheap."
A police officer in Hekou who did not want to be identified said the prostitutes and pimps on Vietnam Street have been far more reserved since a crackdown in 2002.
Now, if a man is with a woman they will not bother him, he explained. Pricing is also pretty fixed, with most charging between 60 and 150 yuan depending on the services required.
"These girls are very industrious and some of them work 24 hours a day. They will all come out in the evening and after 10 pm they can get more aggressive," said the officer.
"It is not just Hekou, though. This phenomenon exists in many places. Honestly speaking, we've done a lot of work on it, such as raids and crackdowns, but these people are just like weeds. They spread quickly."
For Ruan, she hopes her time on Vietnam Street is coming to an end.
"My family doesn't know what I am doing here," she said. "I know I'm doing something without dignity and many people call me names but what other options do I have? Without money, you can't do anything.
"It's worth it to know at least my sister and brother will be able to live with dignity in the future," she added.
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