Sakura lives a double life aboard Megazone 11, a space colony fleet whose master ships are built as realistic simulations of Earth cities such as Tokyo. She is an ordinary second-year middle school student on a satellite ship modeled on a small Japanese provincial town around 2020, and in secret she performs in a singing duo with Eve, a friend she met online. When a resistance movement rises on a master ship, its goal of independence depends on seizing Tiamat, the system that controls the fleet. The key to that system was lost in battle eighty years ago, and with rumors that it has reappeared, both the rebels and the government are searching for it. On a trip to Akihabara on the Tokyo ship to meet Eve, Sakura is caught in a terrorist attack at the station. As Eve guides her to safety from afar, Sakura finds Garland XI, a motorcycle that transforms into a robot, and Eve tells her to use it.