Before the events shown in the anime, the Garan Army, Kiba Army, and Aira Army battled fiercely for supremacy over Machine Island. Despite being a secluded prison, the island possessed significant resources, which the three armies capitalized on by constructing numerous colossal fighting machines. However, the world government uncovered a troubling fact - the island's power reactor was unstable and would explode in 66 hours, resulting in the destruction of all life and the planet. In response to this peril, the government deployed Death Caprice, a team of skilled mercenaries led by Ken Kaido and Ryo Magami, and their imposing robot Mazinkaiser. Yet, was the government's move the right one?