Which term refers to sake that does not fit into one of the four quality categories?

The term that refers to sake that does not fit into one of the four quality categories is indeed Jizake. Jizake is often produced in specific regions of Japan, emphasizing local ingredients and traditional brewing techniques. This category is sometimes considered to represent a more artisanal style of sake, rather than aligning strictly with the recognized quality classifications such as Junmai or the various grades of futsu sake.

In contrast, futsuu generally refers to ordinary sake that doesn't meet specific premium categorizations, while junmai specifies sake made without added alcohol or sugars, indicating a different level of quality. Koji is a crucial ingredient in sake production, used to convert starches into sugars during fermentation but does not pertain to quality classification. Thus, Jizake stands out as a unique category that denotes regional and traditional sake, differentiating it from the established quality designations.