Famed soy sauce production
Long before olives, Shodoshima was known in Japan for its soy sauce production, which has a history of over 400 years. Today there are still a handful of soy sauce factories dotted around the town, perhaps the most famous of which is Marukin. With production happening across several locations one can easily spot the recognizable red and white symbol of Marukin while traveling across the island.
Marukin also operate a museum detailing the history of production on the island, it has useful and easy-to-understand explanations in both Japanese and English, as well as a well-stocked shop where you can buy a wide variety of their goods to take home with you.
(Source: Japan Travel by NAVITIME)