Kroma by Lorenzo De Felici, Volume 1

Imprisoned in a tower within the walls of Pale City, Kroma lives her days out in darkness, believing she is the most evil thing on Earth. However, where her people see a monster, the mysterious orphan Zet sees a human. 

But if either of them are to survive the city’s strange rituals and customs, they will have to overcome the cruel fate of Kroma....even if it means risking certain death beyond the walls in the jaws of giant lizards and enormous birds of prey.