I had to circle Hamahiga Island twice before finding the narrow, earth road. An hour’s drive from Naha, a sign made from sliced bark pointed to Takaesu Seienjo, a salt factory hidden behind clumps of ficus, deigo and subtropical broadleaf trees.

According to records, commercial salt production in Okinawa began in a tidal wetland near Naha in 1694. In a 19th-century guidebook on diet therapy, a physician to the Ryukyuan royal court named Tokashiki Pechin Tsukan claimed that salt, known in Okinawan as “māsu,” “removes toxins, purifies qi energy, and expels lung diseases.”

Masaru Takaesu rakes and sifts through the salt produced at his Takaesu Seienjo factory on Okinawa’s Hamahiga Island. | STEPHEN MANSFIELD
Masaru Takaesu rakes and sifts through the salt produced at his Takaesu Seienjo factory on Okinawa’s Hamahiga Island. | STEPHEN MANSFIELD