Children of the Whales. Volume 3: Abi Umeda

In this post-apocalyptic fantasy, a sea of sand swallows everything but the past.
In an endless sea of sand drifts the Mud Whale, a floating island city of clay and magic. In its chambers a small community clings to survival, most dying young from the very powers that sustain them.
The Mud Whale is in dire trouble. In four days, the imperial apatheia soldiers will return to destroy all its inhabitants. But the Committee of Elders would rather kill everyone on board than wait for the "mercy" of the empire, and the fighters of the island will do the elders' bidding without a second thought. Now Chakuro and the other children are forced by circumstance to rebel against the adults in order to save their home and their lives.
A gripping post-apocalyptic fantasy adventure in the vein of Nausicaa.