Saiga Riki-Oh, fueled by a thirst for revenge and extraordinary strength, embarks on a mission to avenge his girlfriend's death at the hands of a ruthless yakuza boss. His quest takes him to a maximum security penitentiary, divided into four blocks, each under the authority of a Gang of Four member. The initial encounter ensues in the first block where he confronts Hai, a mafia-like knife fighter with inked skin. Tarzan, an enormous and robust man, reigns supreme in the second block, possessing unparalleled physical strength. In the third division, Huang Chaun oversees the gentle yet competent fighting. He secretly grows opium within the prison walls. Finally, the fourth sector's ruler is an unremarkable, diminutive man who prefers to wield needles as his preferred weapon.