It's obviously a win-win deal. Chen Jing, from a third-tier city in Jiangsu province, says she did not know Topshop before but regularly logs on Shangpin.com, which sells La Perla, Diane von Furstenberg and Lanvin. When Shangpin launched Topshop, Chen found the brand is less expensive than those luxury lines but looks trendy and is easy to mix and match with other clothes.

Cui studied at a university in Britain, and so she has bought Topshop for years. She says that after returning to Beijing, she was able to buy it only through a purchasing agent online and it cost much more than the original price.

Zhao says the fashion industry always develops at the same speed with that of society and technology.

He says when a fashion house entered the Chinese market two decades ago, they chose to open flagship stores in luxury hotels where most of their target consumers gathered. Then they looked for local partnerships to open more stores, solving the logistical challenges of delivery and distribution across a huge market.

"Now in the time of social media and a moving digital world, of course, they choose to sell online first," he says.

"Chinese fashion consumers are getting younger. Most are in their 20s and 30s, and there are even some teenagers. They live between the physical and virtual worlds," says Zhao.

He adds that more than 65 percent of Shangpin sales are on mobile devices.

That's why when they launched Topshop, the company organized a two-day promotional campaign titled "Mobile Adventure". They arranged a huge pop-up station at The Place, one of Beijing's trendiest locations, where they displayed some of the latest collections with quick response code tags.

About 5,000 regular Shangpin consumers shop over the app. They also can do a virtual "try-on" and share images on the WeChat messaging platform.