The fantasy manga is set on a fictional island nation named Yakoku, closely resembling Meiji-era Japan, located in the center of the world's seas. The country is currently in the throes of a revolution by reformists pushing for equality, but the conflict has only escalated poverty and inequality. The manga centers on Sezu, a man in the dregs of society who is visited by Kaoru Mamiya, a member of the country's ruling Mamiya family, to serve as his body double.

(Source: ANN, edited)