Li Weiyi, who returns a young wolf to nature in southwestern China's vast grasslands, will see her story hit the big screens on Friday.

Return to the Wolves, a documentary about Li and her wolf cub, recently toured 17 Chinese cities for test screenings, and will be released in mainland theaters on Friday.

As a freelance painter based in Chengdu, the capital of Sichuan province, Li was in the picturesque Zoige grassland in the northwestern province in April 2010.

There, she heard a story about a wolf family from the locals.

The male wolf bit off his own claw to flee from a trap but was killed by some herdsmen, and the female deliberately ate a poisoned bait to kill herself, leaving behind six cubs, born merely a couple of weeks earlier.

Li discovered the only surviving cub, bringing him back to Chengdu and naming him Green.

But city life was not suitable for the cub, and Green also yearned for more space and freedom.

Li released him into the wild, returning him to the Zoige grassland in February 2011.

She wrote a book about the cub titled Return to the Wolf Pack, and the initial print run of 200,000 copies sold out in three months after its launch in July 2012.

Teaming up with Yi Feng, one of her friends and the producer of the documentary, Li spent five years to make the 98-minute documentary from more than 1,000 hours of video clips.

"I lived with Green for 10 months. We did not deliberately guide him to follow orders, just recorded his natural moments and edited them for the feature," says Li during a Beijing event to promote the movie.

Li saw Green again in a video clip sent by locals from the grassland just a few days ago, as she was promoting the film in Shenzhen.

"The last time I saw Green was in 2014. He was accompanied by a female and a cub," recalls Li, adding that she believes an emotional connection between her and the wolf still exists.

Zhao Zhongxiang, a host best known for his hit TV program Animal World, says the documentary is a story which will raise public awareness about preserving nature and saving wildlife.

"Humans have always had a sort of love-hate relationship with wolves, whether in Europe, North America or China. The film is a good attempt to resolve the misunderstandings about wolves. I hope it will teach people more about nature," says Zhao.