Which of the following is not a grade of sake rice?

In the context of sake production, rice is classified into various grades based on its suitability for brewing. The correct response identifies "Shinto" as the term that does not correspond to a recognized grade of sake rice.

Sake rice is categorized primarily by its milling ratio and characteristics that affect the final sake's flavor profile. For example, "Toku-joh", which means "superior grade," is recognized as a high-quality sake rice. Both "Ittoh" and "Nittoh" may refer to certain classifications or distinctions in sake rice although their usage might be less common.

In contrast, "Shinto" does not fit into this classification system; it may refer to something entirely unrelated to sake rice grading or may confuse terms derived from other contexts in Japanese culture, such as Shinto, the indigenous spirituality of Japan. Therefore, it is clear why "Shinto" stands out as the correct answer in identifying what is not a sake rice grade.