From wikipedia: " Groping in crowded commuter trains has been a problem in Japan; according to a survey conducted by Tokyo Metropolitan Police and East Japan Ra

From wikipedia: " Groping in crowded commuter trains has been a problem in Japan; according to a survey conducted by Tokyo Metropolitan Police and East Japan Railway Company, two-thirds of female passengers in their twenties and thirties reported that they had been groped on trains, and the majority had been victimized frequently." can't check the source as it's behind a mobile paywall.