Since late January, Japan has been gripped by a spate of robberies and the subsequent revelations that social media appears to have made it possible for a disparate group of individuals organized from overseas to carry them out.
From the first signs that the same actors could be pulling the strings behind the robberies across the country to the news that the alleged ringleaders were operating from a Philippines detention center, the crimes have shined a spotlight on a recent insidious trend called "yami baito" -- literally "dark part-time work."
Most commonly associated with facilitating offenses referred to as special fraud, in which sophisticated methods are used to trick people into handing over money and valuables, it involves recruiting individuals via social media with promises of big payments.
In the robbery cases, one man prosecuted over an attempted robbery in Iwakuni joined the operation after responding to a posting on Twitter offering a payout of 1 million yen ($7,400) or more a day.
Hideo Okamoto, a professor in criminology at Nara Women's University, warned that there are now countless examples of young people who are prepared to respond to online offers of huge payouts to commit crimes and that social media platforms are making online recruitment easier.
"They have the sense that they are on the periphery, which makes it easier for them to lower their reservations about engaging in crime," he said.
But, he said, their position is more precarious than they realize. "For the people actually engaging in the robbery, the risks are huge, but to the individual coordinating the crime, such people are disposable. They won't be protected. No matter what happens they should stay out of it."
Mikio Uehara, a former prosecutor and now lawyer, said that the groups also make sure to retain leverage over those engaged in their crimes by "exerting mental control that makes it so that those caught up in them can't even think of saying they will leave."
One suspect in a Tokyo robbery believed to have been arranged by the group was quoted as telling investigators that the organization "knew what kind of family I had, knew my house. I felt like I couldn't get out."
According to police, he responded to a call for recruitment and was instructed to send a photo of his driver's license via the encrypted Telegram app. Later, he claimed, a suspicious individual came to his home, leaving him "afraid they could do something to my family."
More than 60 people have been arrested so far for alleged involvement in what an investigative source estimated have been about 50 robberies since 2021. Police say they have also confirmed an unrelated case in 2020 where social media was used to recruit someone to carry out a murder.
Signs of a surge in the prevalence of social media-based illegal recruitment activities were already in evidence in 2021, leading the National Police Agency to decide in May of that year to introduce an investigative artificial intelligence system for speeding up the identification of posts seeking participants.
Attention over the incidents also comes just as the latest NPA figures show that 2022 saw the first rise in recorded criminal cases in 20 years, up 5.8 percent from 2021 for a total of 601,331 incidents.
Among them are a 13.7 percent jump in fraud cases compared to the year before, a 0.9 percent rise in robberies and a 6.8 percent increase in thefts. A survey by the agency also showed that 67.1 percent of people feel public safety has declined in the last 10 years.
In his remarks to the press to coincide with the latest figures, the agency's commissioner general, Yasuhiro Tsuyuki, mentioned the social media recruitment practices by name, saying the NPA will "be vigilant against new recruitment methods and making individuals complicit in crimes."
Referring to the factors behind the first rise in the financial damage done by special fraud cases in eight years, he added that "criminal groups have adapted to societal changes brought by the state of (coronavirus) infections to make their methods more sophisticated."
New steps to tackle the problem are still in the early stages, but in an indication of how seriously they are taking the trend, police have begun to expedite their response.
Among the changes, the start date for the police-appointed internet watchdog to receive new powers to request parties, including internet service providers and site managers, to remove posts has been brought forward from March 1 to Feb. 15.
But because the deletion requests are not legally binding, and providers abroad can assess the illegality of posts based on the laws in their own countries, there are many instances where the content is not removed.
The Hyogo prefectural police in western Japan have also begun preparations to implement an artificial intelligence system to expose criminal online posts as soon as this year, in what appears to be the first initiative of its kind by any Japanese police force.
How officers can surmount the built-in privacy features of apps used by criminal groups will also present challenges.
With the deportation to Japan of the alleged masterminds of the robbery cases completed, a critical factor in the investigation's success is just how much information officers can glean from Telegram, the secure application that the group appears to have employed to arrange its attacks.
Among its functions is the "Secret Chat" option, which allows users to specify when messages sent between parties are to be automatically deleted, with no trace of the exchanges left on Telegram's servers.
Senior officers at the police agency have conceded that overcoming the hurdles presented by secret chat will be "extremely difficult."
Instead, investigative sources say, they intend to exploit group chats found undeleted in the mobile phones of individuals hired to commit the crimes. One such phone was found in a rental car used to flee from near the scene of the fatal robbery of a 90-year-old woman in suburban Tokyo.
But amid renewed focus on measures against rising crime, Mitsuru Fukuda, a professor in crisis management at Tokyo's Nihon University, stressed the importance of more meaningful change.
"In addition to symptomatic treatments such as regulatory measures to aim for a society that is easier to live in, one that does not produce criminals, fundamental remedies such as addressing ways to improve education and narrow income disparities are also important," he said.