Children of the Whales, Vol. 7 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.

The Sea of Sand harbors many mysteries, and an encounter with one of them awakens deep memories of the past for the Eldest of the Mud Whale. But everyone is still reeling from the recently revealed harsh secrets about the true nature of their home. How can Chakuro and the others handle the new knowledge these strange visions grant?