When a string of space mishaps unfold, it uncovers the sinister agenda of the Armanoid extraterrestrials bent on dominating Earth. To counter this threat, Professor Tachibana assembles a skilled team at the Future Science Invention Center. Equipped with five cutting-edge vehicles, Shin, Go, Lisa, and Captain Kenmotsu stand ready for action. Through the fusion of three Tester vehicles emerges the colossal Zero Tester robot, pivotal in repelling the Armanoid incursion across 39 thrilling episodes. The narrative shifts gears in the subsequent series, rebranded as ZT: Save the Earth! (Chikyu o Mamotte!), catering to a younger audience and introducing a fresh menace in the form of the formidable Gallos aliens.