In the early 1990s, mankind began its ascension into outer space. Nuclear and carbon energy have fallen out of fashion and are now replaced with massive solar arrays above Earth that transmit fantastical amounts of power down to the surface via receiver stations.

To keep the peace on a unified Earth stands Interpol: the planet and its energy supply's defenders against terrorism. But when reports from Interpol's Japan branch suggest terrorists are seeking to take control of the power grid, they choose to fight back by resurrecting a weapon they had previously shelved—Tetsujin 28. This giant robot had been created by Dr. Kaneda to prepare for a potential alien invasion, and, through a twist of fate, it ends up being controlled by his son, Shoutarou.

Shoutarou controls Tetsujin 28 by remote and uses his newfound power to fight for good. Together, the two help Interpol fight against vicious monsters, mad scientists, and the cunning Machine Mafia—all while keeping the great steel giant from falling into villainous hands.