Sofia's life a huge hit in cyberspace

Pu says one of the crucial decisions was to hire scriptwriter Ding Ding, who is post-1980 herself and had previously published several books on teenage life.

The production team is also young - Canadian-Chinese director Jonathan Lim is the only 30-something.

The format was created by Portuguese studio BeActive in 2003 and has been adapted for netizens in the United States, Germany, Turkey, Brazil, Chile, Vietnam and United Kingdom.

The format has made a breakthrough in how to make money out of interactive TV. The show collaborates with advertisers to integrate branding - for example, Sofia uses a pink Sony Vaio computer, Clinique for her acne and job-hunting website 51job.com.

The brand placement, Pu says, is not simply to place the product in the settings, but to weave it with the storyline.

For example, Sofia developed acne under the pressure of being in a new city. She asked for help and her stepmother, a beauty editor, recommended Clinique to her. Her friend Beibei, meanwhile, got an internship at a fashion magazine after attending a workshop organized by 51job.

Pu is not worried about being copied by other program makers.

"I would be happy to see more interactive online shows - we still have the advantage of being the first," she says.

"Anyway, the popularity means more chances to develop franchised products, which we will probably do when Sofia becomes a real superstar on the Internet."