Cua Chiu-fai is on a mission to rid Hong Kong's classrooms of what he sees as poisonous anti-China bias. His soldiers: mainly parents. He has recruited hundreds of mothers and fathers to monitor and report on teachers deemed guilty of filling their students with hate for China and urging them to take to the streets in protest.

Using his YouTube channel, which has 114,000 subscribers, Cua says he has enlisted parents and other volunteers as part of an initiative called "Help Our Next Generation." In a video posted in late October, he talks about seeing pictures of "people who looked like teachers" directing young students to pick up bricks during the demonstrations that roiled Hong Kong last year. These teachers need to have their licenses revoked, he says in the video: "If you're a teacher and you make your students destroy this place for certain so-called political positions, that's something we absolutely cannot accept."

Cua's vigilante initiative has won the support of some pro-Beijing political figures in Hong Kong. Targeting the city's teachers has become part of a broader plan by China's leaders to reform the city's rebellious youth after last year's sometimes-violent pro-democracy demonstrations.