But the persistence Sun and her parents displayed in several visits moved him deeply.
"I promised to teach her, but also told them that they could quit at any time if she felt it difficult to follow," he said.
In the following four years, the girl has not disappointed her teacher or her parents.
The lessons are held three times a week and she has not missed a single one.
"Some simple actions seem quite difficult for the little girl, such as a back somersault that needs help from two others," Wang said. "She practiced much harder than others to make up for her physical disability, without any complaints."
The consistent physical training gradually improved the condition of her leg, even though she may never become a perfect actress on stage.
And she has showed great talent in singing Peking Opera.
"She has a good voice for Peking Opera," said her 71-year-old singing tutor, Xing Huizhu, a famous Peking Opera actress in the province. "More importantly, she always diligently practices and can quickly understand what I say."
In May 2017, Sun won her first golden award at the provincial Peking Opera competition after nearly two years of learning, and she won several provincial awards in the following years.
"The awards greatly boosted her confidence in life," her mother said. "She looks just like a shining pearl on stage, which I have never seen before."
After several performances in school, she also became a star among her schoolmates.
"During my first year in school, I seldom went out of the classroom due to my weak legs as well as concerns about being laughed at," she said. "But when my classmates scrambled to take photos with me after the performances, I felt quite proud."
At Wang's suggestion, Ruihan began to learn playing the jinghu, a two-stringed fiddle used in Peking Opera, several months ago.
"A jinghu player who can sing well will have an advantage on stage, and it may help to achieve her dream," Wang said.
Sun said: "I hope I can remain on the Peking Opera stage in the future. I will continue to work hard."
