The film is set in an alternate Japan where street gangs collectively known as the Tokyo Tribes control their respective territories and are in continuous conflict. Mera, the head of the Wu-Ronz tribe of Bukuro, joins forces with the violent and sadistic gangster Buppa of Buppa Town with the intent of initiating a gang war between the Wu-Ronz and the Musashino Saru tribes. When it comes to a confrontation between the two tribes, Mera attempts to kill Kai, a popular member of the Musashino Saru tribe. During the attempt Mera accidentally kills Kai's friend Tera, another member of the Musashino Saru tribe who has been beloved by members of all Tribes since before their formation. This causes all of the other Tokyo Tribes to join forces against Mera and Buppa's forces, leading to an all-out gang war.