Carrying on a Three-Generation Legacy of Seaweed Cultivation in the Ariake Sea
Ariake Suisan is a seaweed farming family business based in Okawa City, Fukuoka, operating for three generations in the rich waters of the Ariake Sea.
The current head, Tetsuya Koga, began helping with the family business at a young age. Upon graduating from university, he took on the role of sales under his father's guidance—and eventually returned to the sea as a full-fledged seaweed fisherman.
The Ariake Sea is a nutrient-rich "Sea of Treasure" fed by over 100 rivers, and about 40% of Japan's nori (seaweed) is cultivated here.
One of the Ariake Sea’s unique features is its dramatic tidal range, reaching up to 6 meters. This creates natural cycles of seaweed exposure to air during low tide, a phenomenon known as "Kanshutsu", which helps the seaweed dry, strengthens its texture, enhances its color, and prevents disease and algae overgrowth.
To enable this process,they manually install over 2,000 support poles, each about 10 meters tall, into the sea for every harvest season.
This traditional method, called “Shichushiki Yōshoku” (pole-style cultivation), is labor-intensive, but they firmly believe it’s the reason Ariake seaweed stands out in quality and taste.
Innovation Born from Crisis
Once cherished as a luxury gift item, Ariake seaweed faced a steep decline with changing times, mass production, and uniform taste preferences.
After the 1991 economic bubble burst and a major crop failure caused by the Isahaya Bay land reclamation project, the seaweed industry began to falter.
Seeing the limitations of simply preserving traditional methods, Tetsuya's father—representing the second generation—set out to create a new style of seaweed.
He visited pioneering producers across Japan, learning and experimenting with his family by his side. But success didn’t come easily.
Nature, especially the sea, is unpredictable. The early years brought repeated failures. Despite working late into the night, many batches had to be discarded.
Still, he never gave up—continuing to innovate, refine drying techniques, and improve equipment.
After three years of relentless trial and error, a new product was finally born: “Shisai”.
Shisai is a seaweed unlike any before.
Rather than being minced and processed into sheets like traditional nori, Shisai is dried in its natural form—preserving its nutrients and deep umami flavor.
Only the finest “first-harvest” seaweed (ichiban-tsumi) is used, giving it a naturally sweet taste and melt-in-your-mouth texture, enhanced by the aroma of the sea.
A Message from the Third Generation
At Ariake Suisan, they manage every stage of the process—from harvesting to forming, drying, shipping, and direct sales.
This has brought us closer to our customers, and for the first time, they’ve begun to hear their voices firsthand.
Messages like, “My child won’t eat rice without Shisai,” or “Shisai completes my miso soup,” deeply moved us.
They reminded us that seaweed isn’t just food—it’s a part of Japan’s cultural identity, and they are responsible for preserving it.
As the third-generation seaweed fisherman, I’ve come to realize the importance of not only producing but also sharing the story of seaweed and the Ariake Sea.
With every sheet they make, they honor our father’s uncompromising standards and listen closely to the voices of nature and our customers.
Looking ahead, they hope to one day pass on the option of becoming a fourth-generation seaweed fisherman to the next generation.
Together as a family, they continue to challenge ourselves, so that the legacy of the Ariake Sea and Japanese seaweed culture endures.
