I took a train to the city of Asakuchi, on the southwestern coast of Honshu, the largest of Japan's four main islands. Marumoto, a tall, good-humored guy, led me into his family's 146-year-old sake works just as his crew was steaming an enormous vat of rice. To make sake, he told me, grains of rice are first milled, or "polished," to remove their outer layers, which can adversely affect sake's flavors. (The amount of each grain remaining after polishing determines the grade of the sake: 70 percent is left for junmai, or "pure rice," sakes; 60 percent for junmai ginjo; and just half of the grain remains for the highly refined junmai daiginjo.) After it is steamed and cooled, the rice is inoculated with koji, a mold that breaks down the starch into simple sugars, which the yeast—introduced next with plenty of water—converts to alcohol. The mixture ferments for months. Then Marumoto's team filters, pasteurizes, and bottles the brew.