This book is described as "a thrilling tale of murder and retribution aet on the wild seacoast of medieval Japan" and "a stunningly powerful Gothic tale" on the cover. This sets up the novel to be more Western than this story truly is. It follows a small settlement that lives at less than subsistence level on the Japanese shore. They fish, gather some vegetation and trade in neighboring towns. One of the ways they ensure survival is by various members of the community selling themselves as indentured servants. Another is through a ritual asking the gods for an O-fune-sama, or shipwreck. The community harvests salt from the sea every winter by boiling down seawater on the shore at night, causing ships to occasionally wreck on the rocks during winter storms.
Isaku is a 9 year old whose father has become an indentured worker, leaving behind the family. Isaku is tapped in his place to take over salt distillation duties, and the story is a detailed look at his life as he matures. It also details exactly what role the O-fune-sama plays in ensuring the survival of the community, and the entirely human reactions to the bounty.
This is a very Japanese story, elegant in its surface simplicity. But that simplicity disguises the attention to detail, and Yoshimura's expert world building that makes the story fascinating.