In the year 2050 mankind is extinct on Earth. The last survivors, five Kasuga brothers, plan to use a time machine and exterminate invader the Killgis before he starts to invade Earth. They travel back in time to 2015 with the design data of the Killgis' giant robot Black Baron and their three powers: a device for identifying aliens, psychic powers, and powered suits. When the brothers arrive at the past, they contact roboticist Kenichiro Kurenai and start to build a giant robot Red Baron. However, Kenichiro cooperates in the manufacture of the robot on one condition. His younger brother Ken Kurenai gets embroiled in a fierce battle over the survival of Earth as the pilot of Red Baron. An Alien vs Reinforced Humans A Giant Robot vs a Giant Robot A fierce battle starts in Tokyo.
