Many years ago Makuta Spiriah experimented on the Skakdi race. His brutal experiments mutilated Skakdi and turned them into angry and adressive creatures.
1-5-1 is one of the most sucñessful experiments. He does not know fatigue and pain, knows no fear and mercy. The perfect killing machine, loyal to its master to death.
Besides the enormous physical strength and endurance he was armed multipurpose combat system, implanted in his arm. This system includes a flamethrower, a harpoon and a small machinegun.