"This is what I consider my job, so I decided to pour more energy into the 'blind pick' service, promoting it on our micro blog and putting it on the front page of our online store," he says.

In March, order numbers suddenly jumped from eight a day to about 80 a day, because "some buyers were extremely satisfied with the books we picked so they posted a message about it on their micro blogs and many of their followers found out about the service," he says. After the initial rush ebbed, the number of orders fell to about 20 to 30 a day.

But the service regained popularity in September, receiving about 70 to 100 orders a day, and on Oct 10, the number of orders reached a record 4,000.

This was because the "blind pick" service was selected by Taobao as a quality product recommended to buyers who like to search for books.

"There were so many orders that we had to close the online service for a while because we needed time to deal with the backlog of orders, otherwise the messages might have been misinterpreted or we may have sent a buyer's books to another mistakenly," he says, adding that they had to ask for help from other departments.

Now that the order numbers have been limited to 100 a day, they are snapped up within a minute.

Some buyers, with high expectations the books will be special, have expressed their disappointment, complaining online that the bookstore just uses this service to sell unsalable books, that the staff members had not understood the message they sent, or that the books sent in return were mediocre.

But Lyu says, "If a customer is not satisfied, we will try to talk to them and explain the reasons for our choices."

Some customers also complained online that the express service was too slow, with some of them waiting for up to 10 days for their deliveries.

One reason for this was the huge number of orders the bookstore received. Another reason was that some messages were so difficult to decode that Lyu and his team had to ask for help in trying to decipher them.

Some messages were about a customer's pop idol, or simply a line from a poem, the lyrics of a song, or sometimes nothing at all.

Once a customer asked staff members to draw a little tiger, they did and posted it on Sina Weibo, a major micro blog platform.