In a similar manner to the production of sake, Aspergillus oryzae is mixed into rice porridge or rice cooked to contain a large amount of moisture, and the mixture is kept overnight (ten to twelve hours) at a temperature of 50-60°C in order to cause the mixture to ferment, thus saccharifying the starch contained within the mixture and creating a sweet taste.
日本酒と同様に米こうじを用い、米の粥、または水分を多めに柔らかく炊いた飯を50-60℃程度に保温し、1晩（10-12時間）程度かけて発酵させ、デンプンを糖化することで甘味を得る。