Sake is one of the few alcoholic beverages in the world that undergoes saccharification. During saccharification, rice starch is converted into sugar by the fungal enzymes found in koji, and sugar is converted into alcohol simultaneously.

This room is where the yeast that produces the alcohol for sake is grown. Steamed rice, koji, water, and yeast are added to make a sake starter, which is then placed in a brewing tank and allowed to ferment, producing sake.

In this process, precise temperature control very is important.