An aging Japanese bike gangster mentors a crop of halfhearted pledges threatened by police pressure. In doing so, he confronts his tough guy past and dwindling options for the future.

After working as a reporter and an assistant at a radio station, Watanabe Yoshimitsu, former leader of the bosozoku gang Black Emperor, returned to his old stomping grounds and began to make a film about bosozoku. At the time, he was 21. The teenage members of the bosozoku group, also known as " Thunder " would get into their revamped motorbikes and cars and race around the city. With the police as their enemies, they ran from patrol cars and did other defiant acts. They would put on outlandish clothing and, as a result of fights with rival groups, were very loyal to other members of their own gang. Every Saturday, they would cruise around, vanish and reappear throughout the entire night with no particular goal. However on 1 December 1978, because of provisions in the new highway transport law, the end was at hand for their " season of running wild. " The film shows them simply continuing to run wild on this last night before the law is to take effect.