Mars

Mars (火星, Kasei) is the fourth planet from Earth. It presumably served as a battle ground between the Klaxo Sapiens and VIRM ten of millions years prior and it served as the battleground between Squad 13 and VIRM.

Characteristics
Mars is named after the Roman god of war (known as Ares in Greek mythology) and is referred to as the ‘'''Red Planet’. '''The latter refers to the effect of the iron oxide prevalent on Mars' surface, which gives it a reddish appearance distinctive among the astronomical bodies visible to the naked eye. Mars is a terrestrial planet with a thin atmosphere, having surface features reminiscent both of the impact craters of the Moon and the valleys, deserts, and polar ice caps of Earth.

It has two moons, Phobos and Deimos; in the series, the Klaxo Sapiens built and installed two satellites in two rocks within Mars’ orbit, both of which share the same names. Mars is approximately half the diameter of Earth, with a surface area only slightly less than the total area of Earth's dry land. The red-orange appearance of the Martian surface is caused by iron(III) oxide, or rust. It can look like butterscotch; other common surface colors include golden, brown, tan, and greenish, depending on the minerals present.

Mars is known to be very far away from earth, with the minimum distance being about 54.6 million kilometers. The total journey time from Earth to Mars takes between 150-300 days depending on the speed of the launch, the alignment of Earth and Mars, and the length of the journey the spacecraft takes to reach its target. Squad 13 was able to reach Mars in less than a day due to using a Klaxosaur Mothership, which has similar but far more advanced technology than humans.

Klaxo Sapiens and VIRM war
The long term war between the Klaxo Sapiens and VIRM had taken place on Earth following VIRM’s invasion of Earth but is at some point shifted within outer space, specifically within Mars’ orbit. It is implied this galactic battle lasted for a long time, as the Klaxo Sapiens were able to build two satellites that granted them access into a Warp Gate. In the war’s climax, VIRM retreated and the Klaxo Sapiens went into hiding within Earth’s core.

Parasites and VIRM battle
60 million years since VIRM’s initial invasion, the alien species reappeared at their leader’s command in order to eliminate the parasites and Klaxosaurs, and destroy Earth. However, Strelizia was able to destroy a large horde of them and VIRM retreated to Mars’ orbit.

A few days later, Squad 13 traveled from Earth for a final battle against VIRM, which ended victorious in Squad 13’s favor as VIRM was once again defeated and Strelizia used the Watp Gate to locate the VIRM home planet.

Trivia

 * The moons, Phobos (panic/fear) and Deimos(terror/dread), are named after the sons of Ares, with whom they accompanied in battle