For many people in Japan, the name Ako immediately brings to mind the famous story of the Forty-Seven Ronin. But another industry played a central role in the town’s history: salt. During the Edo Period, Ako was even regarded as Japan’s leading salt-producing region.

Ako had the ideal natural conditions for salt production. Sand carried down from the mountains by rivers formed broad tidal flats at their mouths. Here, people developed a method known as “irihama enden,” drawing seawater into tidal salt fields to produce salt on a large scale.

The Ikeda family—the same family that carried out the great reconstruction of Himeji Castle—helped drive the industry’s expansion. They built a castle and castle town in Ako and developed its salt fields. After an unfortunate incident involving the head of the family forced the Ikedas to leave Ako, the lords who succeeded them expanded the tidal salt fields even further. Over time, Ako grew into Japan’s foremost salt-producing region.

Local records suggest another connection with Himeji. They say that the people who first developed Ako’s salt fields had previously worked in salt production along the Himeji coast. These workers may have brought their salt-making expertise with them to Ako, helping the town develop the industry on such a remarkable scale.

As salt making spread across the Seto Inland Sea, salt became abundant and less profitable. Shodoshima, another major salt producer, adapted by turning its surplus salt into soy sauce. Shipping routes to Osaka and Sakai helped the new trade flourish, transforming the island into a renowned soy sauce region.