After four years away from home, Shozo returns to Japan to revenge the death of his yakuza boss, who was slain by Kurawaki, Shozo's own traitorous top man. Both men are seriously injured as a result of the combat, and when Shozo recovers in a mystery medical facility, he discovers that his arm has been replaced with an M61 Vulcan cannon and his leg has been replaced with a rocket launcher. Kurawaki, on the other hand, has been fitted with mechanical augmentations that are uniquely his own. Prepare yourself for the second round.