Arrest of Masterminds: Take Step toward Eradication of Anonymous, Fluid Criminal Groups

Editorial

15:12 JST, December 6, 2025

Last year, a spate of robberies, related to “dark part-time jobs,” in the Tokyo metropolitan area sent shockwaves through society. It is significant that the masterminds of a criminal group have been arrested. It is hoped that police will make every possible effort to uncover the reality surrounding the group.

In connection with a dark part-time job robbery that occurred at a private residence in Ichikawa, Chiba Prefecture, in October last year, a joint investigation headquarters involving the Metropolitan Police Department and police in three other prefectures has arrested four men, all in their 20s, on suspicion of robbery resulting in injury and other charges.

The four are believed to be the masterminds behind the incident. They are suspected of conspiring with the perpetrators and others to break into the private residence in Ichikawa, assaulting the resident and severely injuring her, and then stealing cash and other items.

Between August and November last year, there were a total of 18 robberies related to dark part-time jobs, in which perpetrators and others were recruited via social media, in Tokyo, Chiba, Saitama and Kanagawa prefectures. These were serious crimes that shattered peaceful daily lives, causing significant anxiety among residents.

It is the first time that masterminds have been arrested in connection with the spate of robbery cases. The four are also believed to have been involved in cases other than the one in Ichikawa. The hope is that police will clarify the relationships among the four, the chain-of-command in the criminal group and whether there are any connections with other criminal groups in their investigation going forward.

With members being connected through social media, the organizational structures of these criminal groups are difficult to discern. They are called “anonymous and fluid criminal groups” (“tokuryu” in Japanese) and pose a major threat to public safety. Their main characteristic is that members repeatedly come together and disperse, making it hard to identify central figures.

Consequently, it is said that even if perpetrators can be arrested, masterminds remain hidden from view, complicating attempts to uncover them.

The four arrested this time reportedly had been using highly anonymous communication apps, adopting multiple account names to give perpetrators and others specific instructions on such matters as locations for conducting robberies.

Related to the spate of robberies, police have arrested 51 people so far, including perpetrators and those responsible for collecting stolen items from them. Police confirmed the involvement of the four in the Ichikawa case through such actions as analyzing a total of 750 seized smartphones.

The investigation headquarters pieced together fragmented information through over a year of steady investigation, revealing the group’s entire picture. It can be said that enhanced cooperation across prefectural boundaries also contributed to the arrest of the masterminds.

Police nationwide are making full-scale efforts to eradicate tokuryu groups. In October, they strengthened their investigative framework by establishing a new command center to conduct multifaceted analysis of tokuryu-related intelligence.

Amidst these efforts, an MPD inspector involved in the investigation was arrested for leaking investigative information to a suspected tokuryu group. This was a shocking act of betrayal.

Police have no other choice but to take thorough measures to prevent a recurrence in order to restore public trust.

(From The Yomiuri Shimbun, Dec. 6, 2025)