在日本九龍組，寶豪組等幫派黑社會和警察經常發生對峙，年輕有為的佐田上任后，決心要把那些社會的毒瘤給除去，使而得罪了很多黑幫敗類遭到報復，他的女朋友就是因為遭到報復而命喪黑幫之手。為了替女友報仇，他將與黑幫決一死戰。

Police struggle to uncover Klein, a powerful criminal organization. Asuka, a young detective, is assigned to contact and escort Hatsumi, a mistress of the drug lord Kimikuni, but they are ambushed, leaving Hatsumi brain-dead and Asuka near to death. However, the police concoct a top-secret plan to infiltrate Klein by transplanting Asuka's brain into Hatsumi's body.