Everyone at school thinks Sousuke is a hopeless military geek, but Kaname thinks there might be something more to him. When their plane is hijacked, her instincts prove correct: Sousuke is a mech-piloting mercenary, and he's here to protect her!

The Tearmoon Empire has fallen, and its princess, Mia, is executed...only to wake up in the past as a twelve-year-old! Now she has to find some allies, change the future, and spare herself a second gruesome end at the blade of the guillotine!