• The "Secret Garden" coloring book by Johanna Basford has sold millions of copies in China alone.

The "Secret Garden" coloring book by Johanna Basford has sold millions of copies in China alone. (Photo : Facebook/Johanna Basford)

Johanna Basford's adult coloring book "Secret Garden" has been tagged as China's best-selling book for 2015. Introduced to the Chinese market barely three months ago, the book has sold over three million copies.

Chen Lijun, the manager of Dangdang publishing company, revealed that the copies sold already amounted to over 1.5 million yuan. The huge sales made the publisher to call Beijing as the "adult coloring capital of the world."

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In any case, the main reason why many people are buying the book is to relieve stress. In an article on China Daily, Xiong Xin, a staff worker from a company in Beijing, said, "I think coloring is a good way to relax."

For others like Anne Ruisi, a foreigner working in China, they get pleasure from unleashing their creative side through painting and drawing. Basford also thinks that her books are really relaxing and creative so it is popular among adults who are seeking some time off from a hectic day.

"I think it is really relaxing, to do something analogue, to unplug. And it's creative. For many people a blank sheet is very daunting--with a coloring book you just need to bring the color. Also there's a bit of nostalgia there," she said in an interview with The Guardian.

"Secret Garden" was first published in 2013 and since then, it has been consistently topping the list of best-selling books worldwide. Publisher Laurence King even called the fad as a "global phenomenon."

Finally, because it is so popular, the book has been translated into 14 languages and millions have already been sold across the globe. Well-known commercial brands like Sony, Nike and Absolut Vodka have also joined the craze and used the art book in their ads, Mirror UK reported.