Twenty years into the future, the city known as "Tokyo" has grown into one of the world's elite high-tech hubs, now called "Tokyo City." The protagonist, Ken Kanzaki, is a young detective assigned to the criminal investigation division of the Metropolitan Police, recognized as one of the force's top marksmen. One day, Ken is tasked with providing security at a party hosted by the "Zaizen Konzern," a global plutocracy.
Suddenly, spector robots appear and disrupt the event. Zaizen, the commander-in-chief, is killed, while Ken and Jun, Zaizen's son, are critically wounded by the robots. Two other guests—auto racer Ryo Aguri and wrestler Go Goda—also sustain severe injuries. These three gravely hurt young men are operated on by scientists from the Metropolitan Police. Several days later, a robot corps led by a mysterious organization called "Ido" emerges in the floating town of Tokyo Bay. However, the police and army lack effective measures to stop them.
At that moment, three young men clad in mechanical suits arrive. They are the very same individuals—Ken, Ryo, and Go—who have been transformed into cyborg investigators through the surgery. They call themselves "Armored Police Metal Jacks." The "Metal Jacks," dazzlingly shifting from "Jack Suits" to "Jack Armors," completely annihilate the robot corps and secure victory, marking the start of the battle between high-tech criminals and the "Metal Jacks" against the backdrop of a futuristic "Tokyo City."