Mention Shodoshima to the Japanese and two things come to mind: olives and, if they are movie buffs, “Twenty-Four Eyes,” a 1954 picture directed by Keisuke Kinoshita that was filmed there. The second-largest island in Japan's scenic Seto Inland Sea and home to 30,000 people, Shodoshima is one of the best places in Japan to cultivate olives. Indeed, since 1908, it was the nation's first location to do so effectively.

But it is shoyu, not olives or movies, that took me to Shodoshima.

Situated around one hour from Takamatsu, Kagawa Prefecture, Shodoshima is one of Japan’s major shoyu production areas. According to Keiko Kuroshima, a Shodoshima-based shoyu sommelier, the islanders began to make shoyu more than 400 years ago in the early Edo Period (1603-1868), and the local industry grew so much that between 1878 and 1886 alone, there were about 400 brewers.