"I had never imagined we could grow so quickly."

Duo Zhua Yu now sells about as many books as it buys each day, about 20,000, and its customer base has grown to more than 100,000 people, she says.

The online shop's success is built on what seems to be a changing attitude to ownership by which younger Chinese are giving greater emphasis to the right to use things rather than the right to possess them, which means they are more likely to pass on used items to others. Other manifestations of that are rental bicycles and rental clothing.

Moreover, better quality bookbinding gives books more durability, making them amenable to being circulated among different buyers. And due to the improvement of technology, it is possible for the WeChat-based mini-program to easily distinguish different books by scanning its ISBN code to show the price.

Other online secondhand book stores include Zhuan Zhuan (Exchange) and Manyou Jing (Wandering Whale), which have official accounts or mini-programs on WeChat.