Overview of the Crackdown
On February 15, 2023, Fukuoka, Kumamoto, and Nagasaki Prefectural Police carried out a sweeping crackdown on the prostitution ring "Black Diamond" (a tentative name used by investigators), which had been operating widely across Kyushu. In a joint search of the three prefectures, they searched a total of 14 locations and arrested 11 of the ring's executives and middle managers on suspicion of violating the Anti-Prostitution Act (organized/managed prostitution and provision of premises).
The Ring's Scale and Methods
The ring operated through a website under the guise of a "dating club" and "sponsored companionship," along with a members-only closed community using LINE groups. It charged male members a monthly fee and provided sexual services by granting them access.
More than 50 women in total were involved. Each was placed in a state of de facto organized/managed prostitution, paying the ring a set "scout-back" or "management fee."
Sex-Industry Crime in Regional Cities
In response to intensified crackdowns in the major metropolitan areas, illegal sex-industry operations have been shifting to regional cities—a trend also confirmed in this case. Fukuoka City is home to the Nakasu entertainment district and is one of the regional cities where the sex industry is especially active.
This article is compiled based on publicly available information and interviews with investigators.