Mysterious young Daisuke Misaki joins the Scientific Attack Force (SAF), and unbeknownst even to them, secretly transforms into a fire-powered giant from Atlantis, who fights rampaging giant monsters spawned from various phenomena.
In a galactic future where humans have taken over several star systems the legendary hero called Machineman arises to defeat the "Tentacle", an evil organization who wishes to eliminate all children in the world.