Membership of Japan’s once-feared yakuza gangs has shrunk to 30,500, down from a peak of more than 184,000 in the early 1960s, thanks in large part to an ongoing police crackdown on organised crime and public attitudes towards gangs hardening.

The National Police Agency announced that membership of Yakuza groups fell to 30,500 in 2018, down by around 4,000 on 2017 and the 14th consecutive year in which gang numbers fell.

The notorious Yamaguchi-gumi remains the single largest underworld group, with around 9,500 members, followed by the 4,900-strong Sumiyoshi-kai and the 3,700 Inagawa-kai gangsters.

Police investigated 16,881 cases involving underworld groups in 2018, the agency said, 856 fewer than in 2017, with drug arrests still accounting for the bulk of the crimes.

Yakuza control Japan’s drug and sex industries and have traditionally earned a reasonable living aided by loan sharking and protection rackets, while the better oprganised players have used their earnings to set up legitimate companies in the finance and property sectors.

With their roots in feudal Japan, Yakuza still prefer to be known as “ninkyo dantai”, meaning “chivalrous organisations”, and see themselves on occasions as latter-day Robin Hoods. Local Yakuza groups did provide food and shelter in the aftermath of the 1995 earthquake in Kobe and again after the Tohoku disaster of 2011, but they are being increasingly rejected by society.