198X: Freezon Energy is discovered on Earth, splitting Earth into five different zones and the Metra Zone (Japan) is governed by the Landmaster.
199X: The Alien Waruders commenced their attack on Earth to rob the planet of its Freezon Energy. Diaclone was founded to stop the Waruders and engaged into a massive war against the aliens.
Unidentified:
Hikari Kaizaki lost her little brother in the ensuing war.
The Waruders retreated from Earth after their main base on the Moon had been attacked. Diaclone emerged victorious and set up a defense base on the Moon after that.
Meanwhile the Waruders' home planet became a dead planet, but instead of being absorbed into a black hole, it transformed into a monster named Giganter due to the Waruder people's residual thoughts and set forth to advance to Planet Earth to carry out the inhabitants' final wish: to consume the Freezon Energy on Earth.