"I like the (Chinese) culture, and I think I'm different enough that I can keep noticing things and getting inspired," Heijnen says.

In November, Heijnen published his second book, Hong Kong Market Cats. He is now working on two others. One's called Hong Kong Garage Dogs, which is scheduled to be released by the end of the year.

"It is similar to Hong Kong Shop Cats in the sense that the common element in all photos is an animal, a 'functional' animal. My larger aim is to feature the environment these dogs live in-gritty, messy places."

Dogs and cats help people. Hence, they are useful in society.

The other book he's working on is China Shop Cats that extends the phenomenon to the mainland, where he says he is traveling and exploring old neighborhoods in modern cities.

Contact the writer at xuhaoyu@chinadaily.com.cn