Children of the Whales, Vol. 2 by Abi Umeda

In this postapocalyptic 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, cut off from its own history by the shadows of the past.

It is year 93 of the Sand Exile, but the implications of that calendar are only now sinking in for Chakuro. Imperial soldiers from the Allied Empire have appeared out of nowhere with orders to kill all the “criminals” of the Mud Whale! The Committee of Elders knows why this is happening but still won’t explain it to the young Marked of the island. And the elders would rather see the Mud Whale sink forever to the bottom of the Sea of Sand than leave them all at the mercy of the empire.