Loran Cehack, a member of the lunar Moonrace, is sent to Earth as a scout for the return of his people to their mother planet. But Earth's rulers have formed a militia to oppose the handover of their land to these aliens. With their outdated biplanes and fighting vehicles, the people of Earth are utterly helpless in the face of the Moonrace invasion and its huge walking robots. Then Loran discovers a relic from the space age, a mobile suit called Turn A, and becomes the last hope of Earth's militia.

洛兰·切赫克是月球月 race 的一员，被派往地球作为侦察兵，为他的种族返回母星做准备。但地球的统治者组建了一支民兵，反对将他们的土地交给这些外星人。面对月 race 入侵者及其巨大的行走机器人，地球人民的老旧双翼飞机和战斗车辆毫无招架之力。然后洛兰发现了一个太空时代的遗迹，一台名为逆 A 的机动战士，成为了地球民兵的最后希望。