Users of social networking sites such as Facebook and Line are accustomed to receiving a ¡°friend¡± request or a message from an unfamiliar contact. Most people ignore them, but the few who respond may need to think twice before pushing the send button.

Cases of ¡°sextortion,¡± in which victims are lured into sending explicit images of themselves and are then blackmailed by the recipients, have been reported to police and cybersecurity firms, prompting them to raise a red flag.

Cases of ¡°sextortion,¡± a term coined from the words ¡°sex¡± and ¡°extortion,¡± have become more common in the U.S. and other countries such as the Philippines in the past few years. But a sextortion crime ring is now apparently targeting Japanese social media users as well, according to police and cybersecurity companies.