Let's have a look at the other main ingredient of sake making, the rice. Different types of rices are used for sake, we'll not look into the details here. You can read what John Gautner's says on sake-world about the rice varieties used for sake brewing, a very interesting page.
The Himonoya brewery performs itself all the tasks needed to produce sake, including the preparation, or milling, of the rice. In a separate building on the other side of the street in Nihonmatsu, a middle-aged man handles this delicate stage. To be able to ferment properly, the rice must be stripped from its outer shell, and this is done by a mill. In the past is was done manually by stepping on the rice and the kernel were often cracked and damaged, with negative results for the fermentation and the sake. Relatively-modern technology helped here, and the milling machines can mill softly large volumes of rice with the right percentage of outer shell removed.
As you can see on these samples we saw in the Daishichi brewery (next story), the more the rice is milled the rounder it looks.The thing is, this is at the center that the starch is concentrated, and it is the best element for sake making. That's why certain Japanese-grown rice varieties are preferable instead of table rice : this is because these are high-starch rice-varieties. The outer shell of the rice is full of fats and proteins which are not desirable for a good sake, thus it is milled away.