Grados Invasion World

This world takes place in an alternate 1996 where humanity has advanced enough to travel to Mars and the Moon, and establish settlements there. However, the Cold War is still going on, with ever-increasing tensions between United States of America and the Soviet Union, and the threat of a nuclear war looms on the horizon.
But soon, an unknown menace befalls humanity: on Mars, the members of an exchange program funded by the United Nations to promote peace and dialogue between nations find themselves trapped in a crossfire between four mysterious humanoid robots - three of which begin firing on the exchange program's base, killing almost all of the students. Only a few people survive, but they find themselves isolated on an inhospitable planet that has become a battlefield. And, as if this wasn't enough, the pilot of the fourth robot, who had been trying not to involve the civilians in the battle, actually presents himself to the survivors, introducing himself as Albatro Null Eiji Asuka, and telling them that the Earth is being targeted for occupation by the far-away Grados Empire...

Setting

The Story takes place in the year 1996, where humanity is advanced enough to develop long-range space travel, as well as bases on both the Moon and Mars. However, the Cold War tensions between the United States and the Soviet Union have not ended; rather, they've escalated as both sides build military facilities in space, and the shadow of nuclear conflict looms over humanity, both on and off Earth.

Meanwhile, on Mars, an exchange program created by the United Nations to promote peace and understanding is about to begin; the "Cosmic Culture Club", consisting of 16 boys and girls, as well as their instructor Elizabeth, arrives at the UN Mars base, and are being welcomed by the staff. Among the passengers is Anna a 14 year old girl who serves as the narrator for the story.

Suddenly, four unidentified humanoid robots classified as Super Powered Tracers are detected, engaged in fierce combat with each other. The UN base is caught in the crossfire and quickly destroyed, killing all but six members of the "Cosmic Culture Club"--Elizabeth, Arthur, Roan, David, Simone and Anna, and leaving them stranded on an inhospitable planet that has suddenly become a battlefield. As the battle ends, the lone SPT standing lands next to the terrified group and opens up revealing a pilot, who simply announces to them, "The Earth has been targeted".

The robots who destroyed the UN base were the creation of the Grados, an alien race, from the Udoria system, who came to the Sol system for the purpose of conquest, seeing an easy victory as the two superpowers raged against each other to exhaustion—however, this could also be described as an act of pre-emptive self-defense; the Gradosian supercomputers have determined that humanity will eventually cease its infighting and become powerful enough to spread through the galaxy, posing a destructive threat to even the far off Grados.

However, there were two Grados opposed to the plan: human astronaut Ken Asuka, assumed lost during a deep space mission but discovered by the Grados, and his son Null Albatro (his "human" name being Eiji). As the Grados prepared their invasion fleet, Eiji stows away on board one of the ships and steals their most powerful and advanced weapon, the SPT-LZ-00X Layzner before fleeing, seeking to warn humanity of its impending invasion. It was here where he was attacked. Aside from the Layzner, the surviving humans have now become very important to the Grados; as the only human eyewitnesses to the aliens and their power, the six are the only ones who can convince the warring powers to stand down from destroying each other, and focus on the greater threat.

Trivia

The Lonely Way of Melos.

• The Scouters in the manga and anime series Dragon Ball Z were heavily inspired by the "targeting eyepieces" of the SPTs; however, Eiji does not use a targeting eyepiece in the series until some episodes later (originally, he wears a full-face helmet).