An alien overlord, he oversaw an invasion of Earth on several fronts : infiltration, corruption of world governments, frontal attacks, terror incidents and extortion. The organization he led, known as Big Five or Gargoyle depending on the language of the broadcast, was made up of a ruthless group of operatives, some alien like himself, and some opportunistic Humans who seemed to come from every bad corner and movement on Earth. At first, only some world governments knew of this threat, and used operatives to combat it like Japan's Team Unicorn. At a certain point, Guillotine was prepared to use giant mecha and daikaiju to promote his conquest, and on an island fortress, captive scientists built the Giant Robo, a mecha of power, skill and adaptibilty to lead the final conquest of Earth.
A passing jetliner over the island is shot down to avoid detection of the project, with two survivors being Unicorn Agent Juro and a young boy, Daisaku Kusama (Johnny Sokko in the US). Finding the lead scientist, Daisaku is given complete control over Giant Robo. Escaping together, Juro and Daisaku meet up with Unicorn, which recruits the young boy, as the robot's controls are imprinted upon his voice. By the end of this adventure, the heroes use Giant Robo to turn back the attack from the first of Guillotine's daikaiju.
Throughout the series, there was very little that Guillotine did not attempt in his efforts to either control or destroy Giant Robo. The various kaiju often had specialized attacks meant to disable Giant Robo or its systems, but with the support of Unicorn, Daisaku/Johnny learned to exploit Giant Robo's abilities to their fullest. Various stealthier attacks included a robot duplicate of Johnny to seize back control of the robot, poisoning drinking water with an agent that rendered the victim comatose and disfigured, and a corrupted schoolmate of Johnny's who had his own mecha, a Giant Claw. When another Earth government attempted to build its own Giant Robo, Big Five/Gargoyle seized this duplicate and programmed it for their own use.
In the series finale, Guillotine either resurrected or duplicated a number of his fallen minions, Human and monster alike, and confronted the heroes in gigantic form with an added threat. His body was now an energy-laden bomb set to go off if he should be attacked, with a yield capable of destroying Earth. Having no choice, the Earth forces surrendered and Guillotine was triumphant. Yet one last time, though, he had overseen the creation of his own defeat. Ignoring orders from Daisaku/Johnny, Giant Robo seized Guillotine's gigantic form and flew off with it into space, seeking an oncoming celestial object which detonated Guillotine, presumably destroying them both. (Similar to the final fate of Ivan Ooze.)
Emperor Guillotine seemed ruthless towards his subordinates, but this is hard to measure. Due to the effectiveness of Giant Robo and Unicorn, very few of his minions ever returned to face the price of failure.