Killer The Butcher is a merciless leader of the Gaizok invasion of earth and the primary antagonist of the series. Butcher is of an unknown alien race, though it's eventually made clear the race had barbaric warrior tendencies. He will use any means necessary to eradicate the human race and often comes up with despicable schemes to do so. He gets enjoyment out of making humans suffer and purposely prolongs their seemingly inevitable demise by attacking the planet little by little instead of using all of his force at once. He is extremely gluttonous and is almost always eating pieces of meat. He is also very self centred and demands constant attention from his subordinates. He becomes angry when his subordinates fail to carry out his orders but doesn't punish them severely or over-react.

There once existed a planet named Beal, until it was wiped out by the mysterious entity known as Gaizok. The few remaining survivors escaped to Earth and split into three families, named Jin, Kamie, and Kamikita respectively. While attempting to start a new life, the collectively known "Jin Family" prepared for the inevitable Gaizok invasion on Earth and its giant mechanical beasts known as "Mecha Boosts". In order to defend their new home, they have built three vehicles which when combined form the mighty Zambot 3. The Jin Family must not only defend against Gaizok attacks, but also harsh criticisms from the very people they protect, who blame the Jin Family for the invasion in the first place.<br><br>
(Source: AniDB)