For the sake of humanity's tomorrow

Several years after humanity extended its reach to outer space, a planet was discovered that seemed to have once been inhabited and developed by intelligent life. There were high-rise buildings, structures that appeared to be power plants, and it looked just like Earth. However, there were no intelligent beings there; they seemed to have gone extinct.

It was likely that an overly developed civilization had destroyed itself. Earth's humans must learn from this and not repeat the same mistakes. That's what was publicly reported, but the scientists' eyes were evasive.

Since then, there has been an unprecedented robot anime boom on Earth. Many old robot anime that were broadcast in the era when humanity could barely reach the moon, when escaping the solar system was a distant dream, were also broadcast. Boys' eyes sparkled, and many young people answered that their future dream was to be a robot pilot.

Around the time when many young people on Earth aspired to be robot pilots, the International State Alliance announced a shocking truth.

That planet, developed by intelligent life, had not self-destructed. They were destroyed by an external enemy.

Images of the external enemies that destroyed them were released on national news programs. They were grotesque, monstrous beings with forms far removed from any creatures known to Earthlings. Scientists called these monsters the "vaccines" created by the universe's self-purification process.

The monsters, which are the universe's vaccines, are produced when they sense organisms that excessively harm planets in the universe, and they exist to eliminate them as a cosmic infection.

And the next target for the monsters, the universe's vaccines, was Earth's humans. The planet once called Pluto had become a nest of monsters.

On Pluto, the monsters, the universe's vaccines, were being produced daily by something on Pluto. Scientists named the entity that produces these monsters the "Queen Sphere."

Eventually, a large number of the monsters, the universe's vaccines, will come from Pluto and eliminate all of Earth's humans. To prevent this, they had to go to Pluto and destroy the Queen Sphere that produces the monsters, the universe's vaccines.

In response to this emergency, all the countries on Earth declared a truce and united humanity's total strength to take countermeasures. A space battleship was built to repel the monsters' attacks and go to Pluto to destroy the Queen Sphere, combining the knowledge and technology of space engineering that all countries possess.

And, to protect this space battleship and destroy the Queen Sphere together, the development of steel giants, humanoid robots, was underway. These developments utilized advanced 3D printer technology, which had been improved and refined to the point where it was said that nothing could not be produced.

Even robots made of non-existent metals that appeared in anime could be recreated by inputting existing metals as materials and reconfiguring them to have similar properties. Some scientists believed that this 3D printer technology was the reason why the universe considered Earth dangerous and sent vaccines.

And, as propaganda to gather those who would pilot these robot weapons, robot anime was broadcast around the world. Before the fact that humanity would be destroyed if they did not win the battle on Pluto, many volunteers appeared.

{{user}} was one of those volunteers.

The volunteers would live inside the space battleship heading to Pluto.

To ensure that the volunteers were not inconvenienced, the space battleship provided an environment as close as possible to what they had on Earth. Meals were provided through onboard farms and ranches using solar lamps, and some radio waves were provided for communication with Earth, allowing communication with those left on Earth, and the acquisition of various software through downloads, although package software was not available.

To increase the survival rate and win rate of volunteers who lack practical experience despite their sense of mission, there is a buddy system that is based on two volunteers fighting together. This is broadly divided into two types: Type A, which has high firepower and armor, and Type B, which has high mobility. It was a system where pilots cooperated with pilots of a different type than the one they were piloting to support each other.