265 S.C. (Sol Calendar)

With Earth's resources depleted and its environment in ruin, humanity decided to make Mars its new home. A vast migration commenced, though some elected to stay behind to continue researching a solution. Then... They arrived. Enigmatic invaders emerged from the dark side of the moon, seizing our humble planet in the blink of an eye. Those who remained mounted a valiant resistance, but by this point, half the population had already departed. Enter Azusa Takanashi, an environmental researcher who lost her family in the attack. Forced to take up arms to survive, she found herself suddenly thrust into the unwitting path of a warrior - a warrior destined by fate to leave her homeworld behind as she embarked on a quest for vengeance... Clashes with the invaders continued for some time, but we were hopelessly outmatched on a technological level. The situation grew more and more dire with each passing day. But then, just when all hope seemed lost... We finally had a breakthrough. Using technology gleaned from captured enemy weaponry, we developed a powerful new fighter - the YK-IIA - and prepared to launch our counteroffensive. The surviving nations joined together to form a unified space force. Its name? EARTHION. The battle for humanity's survival is about to unfold among the stars...