Dr. Haneda was building experimental giant robot warriors intended to fight for the Japanese side in World War II, but before his creations could be deployed, Allied bombing raids destroyed the facility and killed him. Ten years later, criminals located two surviving prototypes—numbers 26 and 27 in the series—and used the remote-controlled machines to pull off various crimes. Twelve-year-old Shotaro Haneda, the doctor's son, investigated and learned that the gang was searching for the twenty-eighth robot in the line, believed to be the most powerful of all. Racing the villains, Shotaro found the robot first, alongside Dr. Shikashima, a former colleague of his father who had also been presumed dead in the Allied attack. Together they kept Tetsujin-28 (the robot’s official name) out of the criminals' hands and decided to dedicate it to peaceful purposes instead of warfare.
For a long time afterward, Shotaro fought crime with support from Dr. Shikashima—who repaired Tetsujin-28 whenever it was damaged—and police officer Otsuka. Eventually, Shotaro even faced the alien Magmans, invaders from the planet Magma who arrived on Earth late in his career, bringing their own giant robots, Magma X and Gold Wolf.
