1.
groper; molester; sexual offender on public transport
A person who commits groping or other forms of sexual harassment, especially on crowded trains or in public places. Also refers to the act itself. A persistent social problem in Japan that has led to women-only train cars and anti-groping campaigns.
Usage
Refers both to the person who gropes and to the act of groping. 痴漢に遭う means "to be groped" (to encounter a groper). 痴漢をする means "to grope someone."
Cultural note
Groping on crowded trains is a recognized social problem in Japan. Many railway companies have introduced 女性専用車両 (women-only cars) during rush hours. Posters warning against 痴漢 are common in stations. False accusations are also a concern, leading some men to keep their hands visible on trains.