fixer; troubleshooter (yakuza)
Yakuza slang: a person or group responsible for handling problems caused by subordinates, often by negotiating or using force. Not used in polite contexts.
The gang's fixer settled the trouble.
tail rider (biker gang)
Biker gang slang: the member who rides at the back of the formation, tasked with blocking or distracting police to let the others escape. Cross-referenced with 暴走族.
See also: 暴走族
The biker gang's tail rider obstructed the police car.