Shodoshima is famous for producing soy sauce. There are 5 production centers of soy sauce in Japan. One of them is Shodoshima, the others are Noda and Tyoshi in Chiba, Tatsuno in Hyogo and Ono in Ishiwaka. Soy sauce is one of fermented foods and one of the most common seasonings in Japan. Soy sauce is made from soybean, wheat and salt. Soy sauce was made in Meiji Era (1868-1912). When we eat sushi and tempura, we usually dip them on soy sauce or put it on top.
In Shodoshima, there were 400 soy sauce factories in Meiji Era but as on now only about 10 factories are running in traditional productive ways. Some of the old factories are registered as a cultural building.
Marukin soy sauce factory makes soy sauce using wooden cask as shown in the picture.