天手让叶是名女高中生，在空中的宇宙殖民卫星过着平静的生活。
但在遇到难民少女尼娅安后，她被卷入了非法MS决斗竞技《军团战》之中。她化名《玛秋》参赛，驾驶着GQuuuuuuX，每日投身激烈的战斗。
同时，被宇宙军和警察两方追捕的神秘MS《高达》及其驾驶员──少年修司，出现在她们面前。
接着，世界迎向了新时代。

In Universal Century 0079, the Principality of Zeon declares its independence from the Earth Federation government, igniting a state of war. In the initial stages, Zeon forces gain the upper hand with their powerful new weapon, the mobile suit. However, their inability to fully conquer Earth leads to a prolonged stalemate. Eleven months into the war, the Federation Forces captured a base in Zeon-occupied Eastern Europe. In response, a Zeon composite battalion is dispatched to reclaim the base. Among its members are Captain Solari and her Red Wolf Squadron, a newly arrived mobile suit team from space. Which side will finally emerge victorious?

A pure-hearted girl from the remote planet of Mercury enrolls into a school run by the corporation dominating the mobile suit industry.