• Jiji


A nationwide police campaign is underway in Japan to issue warning replies to social media messages suspected of links with crime because of the coded language used in them.

A large number of dating messages are posted on Twitter by women seeking money from partners in practices known as enjo kōsai (compensated dating) or papa katsu (sugar daddy). Posters are thought to include many girls younger than 18 years old.

There were juvenile prostitution scandals involving 311 children in 2020, up 45% from a decade earlier, according to the National Policy Agency.

In October 2018, the Aichi Prefectural Police, in a first for Japanese law enforcement, began to send replies from its official account to Twitter messages suspected of links to juvenile prostitution, telling children that “meeting an unknown person is extremely dangerous behavior because this may lead to abduction, murder or other serious crimes.” To adult posters, it warns that sex crimes against children constitute “extremely malignant human rights violations.”

After the Aichi police wrote more than 1,500 replies in the first year of the campaign, many of the messages that received warnings were deleted. The practice was highly praised on social media sites.

Considering the campaign effective, the NPA instructed other police across the country in January 2020 to introduce similar programs.

On Twitter, there are also messages with phrases such as “dark part-time work” and “consignee” possibly to solicit people to collect money from victims in remittance scams, commit robberies or forward mobile phones for use in crime.

Aichi police began to send replies to such messages in August 2019, followed by other police across Japan. Tokyo’s Metropolitan Police Department tells readers of the messages not to respond, putting up warnings such as “the high pay is fictitious,” “the risk of being arrested is big” or “the culprit will know your face, address and family and will threaten you if you refuse to participate once you respond.”

Twitter is also used to sell and buy illicit drugs via messages carrying code words such as “vegetable” for cannabis and “hand push” for face-to-face sales. There are so many messages that they cannot be fully screened by people.

In the current fiscal year through March 2022, therefore, the NPA began testing a system to use artificial intelligence to recognize secret words and messages for drug trafficking efficiently in order to ask Twitter to delete them. The system is also expected to help the police issue warnings faster than it does now.

“After examining the results of the experiment, we will consider how to operate the system in earnest and expand its use beyond drug-related messages,” a senior NPA official said.

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