In the Tokyo City of twenty years from now, investigator Ken Kanzaki ranks among the finest marksmen in the Metropolitan Police. A security detail at a party for the powerful Zaizen Konzern turns deadly when phantom robots strike, killing the group's head and gravely wounding Ken, Zaizen's son Jun, auto-racer Ryo Aguri and wrestler Go Goda. Police scientists operate on Ken, Ryo and Go, rebuilding them as cyborg investigators. When a robot corps sent by a mysterious organization called Ido attacks a floating town in Tokyo Bay, and neither the police nor the army can stop it, the three appear in mechanical suits as the Armored Police Metal Jacks. Shifting from Jack Suits into Jack Armors, they crush the robots, launching a mecha action battle against high-tech criminals across the futuristic city.