A Lie from Beyond

She was born into a world where humanity had been slaughtered by its natural enemy, and the few survivors could only huddle inside a paradise called the "Sky City," living in blissful denial. As a soldier of the Human Empire, her duty was to protect this last paradise. One day, however, someone told her that the truth of this world was a web of lies, each one linked to the next. Her duty was fake. Her memories were fake. She wasn't one of this world's "people," and she might not even be "human." After hearing that, she believed it halfheartedly and decided she might as well quit. But in the end, she had to carry all those lies with her and save a world woven from them. "What is humanity's natural enemy?" "Microorganisms with higher intelligence: disease." "No. Humanity's natural enemy is humanity." - Serious science fiction, sometimes soft and sometimes hard, with plot first and romance later - The heroine has no golden fingers, and excels at snatching defeat from the jaws of victory and showing off - Set a thousand years after In the Midst of Enemies, but can be read on its own Theme: Technology creates the future