The Song of the Fireflies - The Song of the Fireflies, #1

Up above the clouds, where Empires, Kingdoms and Duchies rule the floating islands of the Endless Skies a thief is  tasked to procure a strange box. One which will suck him into a mysterious plot which will change his life forever. Amidst the horrors of the night sky and the forces of the Empire, Viento will have to face his childhood demons... memories he has thought buried for decades.