The city is called Aerith, a floating metropolis that hovers above a long-forgotten Earth, now covered in clouds and acid mist. Emotions are outlawed because they're said to have "destroyed the old world." Every citizen wears a SynMask that regulates expressions and monitors neural responses. Feel too much? You're flagged. Feel too much too often? You vanish. 

No one knows what's beneath the city. It's just called Below. 
But two girls are about to find out.