Wang has particular requirements for selecting each breakfast store. It has to be a regular spot for neighbors nearby and it's usually a family business that has been run by two generations.

"I often pick a store that only focuses on one dish. If a family makes a dish for two generations, it is undoubtedly good food," he says.

In the first three seasons, the store owners were mostly born in the 1960s and '70s. The new season sees some born in the '80s.

Wang could tell the younger restaurateurs have more hobbies and are less burdened than the older generation, "but they all work so hard".

In one episode, Wang records the story of a young couple running a sheep intestine soup store in Cangzhou, Hebei province, and the wife is weeks away from giving birth.

She comes to the store every day with her husband, even though her feet are swollen. Crammed in the small store, they don't complain or grumble, yet they joke with each other every day.

"I guess there is a romantic reason, perhaps the wife wants the unborn baby to hear the father's voice as much as possible and get a feel for their store," Wang says.