BBC reporter confronts man who sells groping videos
Women who are groped on trains in East Asia face the further threat of their assault being filmed and uploaded for sale online.
In a year-long investigation, the BBC World Service's investigative unit, BBC Eye, has gone undercover to unmask the men cashing in on sexual violence.
In this video, reporter Zhaoyin Feng confonts "Maomi", a Chinese man in Tokyo who created his own porn sites with "metro" content.