The number of rowdy motorcycle gangs, or "bosozoku," rose in Aichi Prefecture for the third straight year last year, to about 2,800, the worst in the country, according to the National Police Agency.
While biker gangs with up to 100 members are disappearing, smaller groups whose members swarm around on motorbikes have been on the rise.
Biker gangs rose 33 percent from January to May from the same period last year.