Yang began to help Yao write, first to make his handwriting more presentable, and then tried to fixed his grammar and words to make every sentence understandable. She stops at Yao's stand whenever she visits the market.
In his story, Yao writes a lot about his second son, Yao Wuyi, 15, who is studying martial arts at a school in Beijing. While writing about the boy, he discloses stories about the whole family of six people, who left their hometown and earned a living in Beijing.
"My son, Wuyi, was passionate about martial arts when he was 3. He imitates the security guards training nearby," Yao recalls.
At that time, Yao was often bullied by vendors and migrant workers because he was a newcomer. Not able to fight back for years, Yao decided to send Wuyi to a special martial art school so that he could protect himself in the future.
The talented boy progressed rapidly at school. In 2009, he attended several competitions in Hong Kong, and goes abroad to countries including Japan and the United States.
But the school costs the family 16,800 yuan ($2,700) each year. His other two kids go to normal schools in Beijing, but have few new clothes.
"Most of the clothes my wife and I wear were given by other people," Yao writes in his diary. "But I feel more than happy, as long as I know my children are doing well in school."
Yao's idea of keeping a diary of the family originated in pride for his son.
"At first, I wanted to put down how Wuyi grew up," Yao says. "But as I wrote it, I strongly felt it was a history of our whole family."
"His writing is much better now. He is a very hard learner," Yang says.
Yao always keeps a notebook in his pocket, in which there are tens of thousand of characters recording what he has read each day.
"I love reading books whenever I am free," he says. "I do not know much, but I feel many of life's principles in the books are good and convincing. So I put them down in my notebooks."
Yao loves to read some of his most-loved quotes to people who come up and talk about his writing.
"I have three children and I can support all of them to go to school," he writes. "Our whole family lives together. This makes me feel happy and satisfied no matter how hard I work."
But Yao's wife Li Rong is not at all happy about Yao's writing. The 40-year-old smiles at every visitor to the house they live in, a three-room single story house that the family rents in the suburbs of Beijing, but then frowns and complains a lot about her husband's passion for writing.
"I said to him, you only did four years in primary school. How many characters can you know? Are you able to write good sentences? Are you dreaming about becoming a writer? I'm mad about him writing all day."
Li says she even tore Yao's work to pieces once, which caused a family crisis.
But what happened recently surprised Li greatly.
Since early September, Yao's 200,000-character family history has been reported by Xinhua News Agency, and other newspapers and TV programs in Beijing.
As a result, Yao quickly became a popular figure in the market, as the market manager put newspaper reports about Yao in large print, on his stand.
His fellow vendors who call him "Mr Ginger" now congratulate him on his literary efforts.
"You are amazing," says Li Shengqi, who lives just five minutes walk away, "I did not realize it was you on TV until my grandson noticed. Good job! Very few people can insist on doing some thing with such strong perseverance."
"My children have no idea about my writing," Yao responds. "I will continue to write and let them know about the stories on the day they go to college."
Contact the writer at zhangyue@chinadaily.com.cn.