Black Abyss. Volume 1. Edge of the Sky

The islands of Skyland hover above poisonous black clouds, and the worst thing is to be below, at the edge of the abyss. There, no one will protect you from the giant metal serpents capable of destroying an entire district... in one blow.
 
Sixteen-year-old Konrad dreams of avenging his uncle, who has seized the ancestral estate atop the island. But, exiled to the Lowlands, Konrad is forced to strike a deal with his uncle for his sister, whom he has kept to raise.
 
He passes the selection for the Hunting Guild, where harsh training, rival intrigue, and deadly Competition await him. To fulfill his part of the bargain, Konrad will have to kill as many sky monsters as possible and prove that he deserves to become the captain of a ship. This is not so simple when there are traitors on board. However, Konrad does not yet know that the most serious threat lies beneath the black clouds...