During the first few decades of the space era, humanity was able to exist in a relative peace. But soon rogue organizations collectively known as space pirates began to terrorize space stations. This led to a series of violent conflicts. Both sides developed various types of giant mechs operated by human pilots, called "Metal Movers". A special police force was founded to combat the pirates. The young pilot Gingie and his lovely companion Windy must defend the space station and eventually venture into enemy territory.