A man reads a xiaorenshu at Liu Yanbo's shop in Beijing. Photos by Jiang Dong

The interest in xiaorenshu peaked between 1955 and 1965. There was not much market demand for Chinese paintings at that time and many artists had to supplement their income by drawing xiaorenshu, getting up to 100 yuan (US$13) per book.

Liu considers titles such as Wusong Fights Tiger (Liu Jiyong), White-haired Girl (Hua Sanchuan) and Dramatic Changes in a Mountainous Village (He Youzhi) as classics of the genre.

Besides Chinese literature, famous Western works were introduced to xiaorenshu, such as The Red and the Black, War and Peace and Camille.

"The xiaorenshu was important as we didn't have much choice of entertainment in the 1950s. With vivid illustrations and simple captions, the books were easy to read and therefore welcomed not only by children but also by adults," Liu says.

"What's more, China was closed to the rest of the world at that time. The book was like opening a window on the outside world."

The genre became less popular during the "cultural revolution" (1966-76) and few xiaorenshu were published at the beginning of the 1970s. The stories were usually about heroic workers, peasants and soldiers.

Liu applied to study in the department of illustrated books and New Year pictures at the China Central Academy of Fine Arts, but was turned down. He majored in oil painting instead.

Even so, his passion for xiaorenshu never faded and Liu embarked on a project to write a book about the subject. He was so focused on the task, he locked himself in a house with two other classmates for three months and hired a maid to cook for them.

Disappointingly, publishers were not interested as the audience for xiaorenshu had declined, due in part to the fashion for Western-style cartoon books. Eventually he sold the rights to a collector for 7,000 yuan ($944).

"My first instinct was to run away as fast as I could, just in case the buyer changed his mind. But now I realize how precious the rights are. I wish I could buy them back at 10 times the original price, but it will never happen," Liu sighs, shaking his head.

Liu established an advertising company after graduating but this failed and instead of being a painter he became an electrical appliance salesman. Six years ago, however, Liu was strolling around the antique market at Baoguo Temple when his attention was caught by an old series of xiaorenshu named The Kingdoms of Eastern Zhou Dynasty.

He was shocked to find they were priced at 800 yuan ($108), several hundred times the original price. Liu saw the business opportunity and opened his first xiaorenshu store the same year, at Baoguo Temple.

Since then he has collected some impressive titles. Wusong Flights Tiger (1950s' edition) is one of them, which he bought for 2,500 yuan ($337). Today it is worth more than 20,000 yuan ($2,700), but Liu says he will never sell it "no matter how high the price goes. There are no more than three of these books left in China".

Liu moved his shop to its present location in 2004 and despite the fact that the xiaorenshu business is flourishing, he warned that sometimes the titles do not reflect their real value, as some people are making profits through speculation.

Currently, the majority of his customers are male, middle-aged and above. He said he sold about 500,000 titles a month, on average.

Foreign visitors also show an interest in xiaorenshu, Liu says, adding he was asked to exhibit at a book exhibition in Germany last year. His only slight regret is his daughter doesn't show an interest in xiaorenshu, preferring modern comics and horror stories.

"Young people don't understand our feelings about xiaorenshu. For our generation, it is much more than just a book," he says.

Currently, Liu's personal collection of xiaorenshu is more than 3,000. He is thinking of opening a xiaorenshu museum to share his passion for the art form with the rest of the world.