Bōsōzoku
Bōsōzoku (暴走族) (literally "speeding tribe", known also as kamikaze bikers) is a Japanese subculture very similar to car clubs: gangs of young men who share a common interest in designing (often illegal) modifications for cars and motorcycles.
Among their activities is shinai boso: it consists of driving down the streets at high (illegal) speeds. It is not properly a race; mostly, it is done just for the thrill of it. With many cars (or bikes) involved, the leading one is driven by the sento sha (the leader), who is responsible for the event. Nobody is allowed to overtake him. Others keep a lookout for side and rear cars/bikes.
Bousouzoku members tend to be perceived as criminals and misfits, and they are commonly said to be recruiting grounds for the yakuza, but mostly that is only the impression they want to give. Very few bousouzoku members are older than 20 as they are then considered adults by the Japanese Law system and can earn a criminal record. Bousozouku members older than 20 are considered immature and childish. Japanese society assumes that their activities are a way to relieve the stress of the teenage years.
Bousouzoku were first seen in the 1950s when the motorcycle gang Hells Angels was very active in the USA and thus influenced the Japanese youth and the Japanese gangs.
It is a common opinion that bousouzoku gangs are a gateway to the yakuza. The yakuza often scout these youth gangs themselves.