Posters for the second and fifth episodes and that for the series in general. To attract young people－the main viewers of the platform－many comics, cartoon and animation effects are added in the series.[Photo provided to China Daily]

Drawing younger viewers

A cartoon element is one of the highlights of the documentary-in each episode, cartoon segments are used to illustrate stories being recounted by interviewees, whether it's the stick figure of a book editor as he appears in his dreams, or a picture book author walking into the wonderland he's created.

"The stick figure of Zhu Yue was actually drawn by himself," Luo says.

The cartoon production occupies about 15 percent of the total cost, but its inclusion was a strategy calculated by Zhu Xianliang when planning the documentary.

"On Bilibili, around 80 percent of our users are aged between 18 and 35, so the documentary should be interesting for them," he explains.

He says the users on the platform are mostly well educated and are willing to pay for the content they like.