In Okinawa, Japan, the Tokko Shrine honors a sailor named Maeda Riemon for bringing sweet potatoes to Japan in 1705. He had encountered this plant—which isn’t actually a potato—in the Ryukyu Islands of the South China Sea, where locals called it “Chinese potato.” Riemon was so impressed by the flavor that he brought tubers home for his garden. Before long, Riemon’s neighbors began growing sweet potatoes, and they spread vigorously throughout Japan. They produce huge yields, and the crop is easy to stockpile and store. In those days, crop failures and famines were common, and the Satsuma-imo, as it was called, fed millions of people through harsh times, including World War II, saving many thousands from starvation….