While much of Sunflower's sake is categorized into specific rice collections (ex. Yamadanishiki, Omachi), Shuzokotekimai is the general term for sake rice and refers to any sake made from a registered sake rice variety.
Shuzokotekimai has been bred or developed specifically for sake brewing, and is officially registered as such in Japan. Breeding is either manual, as in cross-pollination, or irradiation, as in Miyamanishiki. To be specialized for sake brewing, Shuzokotekimai is typically high in starch, low in protein, and with large grains. It isn't considered palatable for eating at the table, because it lacks the protein and minerals that would make it delicious to eat plain.
Shuzokotekimai, sake rice, has become a focus of regional and prefectural research centers seeking to differentiate local sake in a competitive market. For example when a sake is made with Aomori Hanafubuki rice, that is affirming for Aomori farmers and brewers alike. They can decide who gets their rice and where it is grown, perhaps limiting the growing area to the prefecture alone. Taking this a step further, some regions have developed official GI (Geographic Indications) for their sake, incorporating local rice in the definition of the GI (ex. Yamagata GI: Dewasansan rice). This is one step in the long process of breweries developing a unique identity in the eras following WW2.
