He had lived for a millennium inhabiting the Skin of the recent dead. His life was ever shifting. He flowed from one host body to the next, uncaring about his perceived death or those he left in his wake. But when humanity grows too arrogant and ruthless, the consciousness of the sea decides to take revenge against mankind and force him to act as her instrument of vengeance. 

He is left in an ocean turned red with blood, in an unfamiliar land, with a companion that he created by ripping the soul from a dying animal and shoving it into the body of the man.
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Readers can expect world-building, mythology, found family, and an exploration of Japanese culture and history in the late 1600s to early 1700s.