But as Nemoto-san shows me around the factory, I learn that the type of rice used, and how it is prepared, are of equal importance. He explains that as sake rice grains are larger and contain more of the starchy white core than table rice, they yield more sugar, and thus more alcohol. But before the rice can be used, it is necessary to remove the outer layers, which contain undesirable lipids and proteins. There are several grades of sake, and how a sake is classified depends mainly on how much the rice is polished. To make ordinary (futsu) sake, for example, less than 30 percent of the rice is removed; for the highest grade (dai-ginjo), that number exceeds 50 percent. After polishing, the rice is washed, steeped in water, drained, steamed, then cooled. Next it is moved into a double-walled, saunalike room and inoculated with koji spores. The koji rice must be gently tossed every six hours for two days, which does much to determine the flavor of the sake and the success—or failure—of fermentation.