Donning a special mask, a young man defends the planet.

The adventure of Hepoi, a hero of heporis, Ryuuto, the prince of Dragonia, Miiya Miiya a fairy looks like a cat, and Bunzaemon, a merchant, to defeat Dracunes, the King of dark side castles.

Twenty years into the future, a city now called "Tokyo" has developed into one of the few world-class high-tech centers, "Tokyo City." The main character, Ken Kanzaki, is a young investigator assigned to the criminal investigation section of the Metropolital Police. He is one of the finest sharp shooters in the Police.One day, Ken is ordered to provide security for a party held by for "Zaizen Konzern," a world-class plutocracy. All of a sudden, spector robots appear and distrupt the party. Zaizen, a commander-in-chief, is killed and both Ken and Jun. Zaizen's son,are fatally injured by the robots. Two of the party's guests, an auto-racer, Ryo Aguri,and a wresler, Go Goda, also receive serious injuries. Three severely injured young men are operated upon by scientists from the Metropolitan Police. Several days later, a robot corp led by a mysterious organization called "Ido" appears in the floating-town of the Tokyo Bay. But the Police and the Army have no effective strategies to contain them. At that moment, three young men attired in mechanical suits enter. They are the very three young men, Ken, Ryo and Go, who have been turned into the cyborg investigators through the operation. They call themselves "Armored Police Metal Jacks". "Metal Jacks," dazzlingly switching from "Jack Suits" to "Jack Armors," completely demolish the robot corp and achieve victory, thus signals the beginning of the battle between the high-tech criminals and "Metal Jacks" with a futuristic "Tokyo City" in the background.

After a slumber of 12 millennia, the Demon Empire returns to seize control of the Earth. Reideen, the giant robot-like protector of the lost continent of Mu, senses the evil presence and awakens within its golden pyramid, revealing to young Japanese boy Akira Hibiki that he is the one descendant of the ancient Mu people who must help Reideen save Earth. He was assisted by his friends, token girl Mari Sakurano (daughter of a scientist fighting the Demon Empire) and several members of his high school soccer team.