The grade is defined by how well the rice is polished. For the sake fermentation, the starch, which is the main nutrient of rice, is necessary, however, other nutrients like proteins, fat, and vitamins are contained in rice.
Normally those nutrients are not directly necessary for fermentation, however, they can produce a variety of flavors and add thick layers of taste. Sake brewed with highly polished rice tends to have aromatic and smooth taste, and it is also more expensive and quantity is limited. Less polished rice makes for more complex and full-bodied sake.
TASTE：Sweet and smooth
Highest grade, so that its expensive but the taste is very delicate and smooth. Fruity aroma is distictive.
TASTE：Medium sweet and dry
High-cost performance, we can enjoy good points of Junmai daiginjo and Junmai. The balance of taste and aroma is well-designed
The layers of taste is the point of this type. The complex and dry taste is also suitable for hot sake.