Sadamitsu: The Destroyer - The Complete Collection - Region 1 DVD

After a cosmic prison break, a horde of murderous aliens are free and headed to Earth. Humanity's only hope, a robotic police officer with unparalleled strength and an unwavering devotion to justice, has been decapitated. Sadamitsu, a local gang member and all-purpose thug, takes up the robot's mission and his head. Wearing it as a helmet, Sadamitsu borrows the robot's powers and fights the attacking aliens.