In the story, a legendary powerful team called Mugen once dominated a town. The group faced resistance from the formidable Amamiya Brothers, the only ones willing and powerful enough to not give in. In the end, Mugen suddenly disbanded and the Amamiya Brothers disappeared without a trace. Afterwards, a group of five gangs—Sannou Hoodlum Squad, White Rascals, Oya High School, Rude Boys and Daruma Ikka—take over, calling themselves "G-SWORD" and naming the area "SWORD" after their gang names.

(Source: ANN)