• Sterilize the Equipment (Crucial Step)

  Sterilize your containers and mixing utensils with boiling water, then let them air dry completely.
  

Mix the Ingredients

• For the Without-Rice Method: Break up any clumps in the dried rice koji. Thoroughly mix the koji with water (or warm water at around 60°C / 140°F) in your container.
  
• For the With-Rice Method: First, mix the cooked rice and water together. Then, break up any clumps in the rice koji, add it to the mixture, and stir very well.
  

Fermentation Process

• Ferment the mixture at 60°C (140°F) for 6 to 8 hours. You can use an oven with a low-temperature/fermentation setting, a yogurt maker, or a rice cooker.
  
• Using a Rice Cooker / Yogurt Maker: Put the mixture into the rice cooker inner pot. Leave the rice cooker lid completely open, cover the top with a clean, damp kitchen cloth or paper towel, and set it to the "Keep Warm" (保温) mode for 6 to 8 hours. (If using a yogurt maker, simply set it to 60°C).
  

• Mid-way Stirring

  After about 1.5 to 2 hours of fermenting, open it up and give it a thorough stir, flattening the surface afterwards.
  

• Adjust the Moisture

  Different brands of rice koji absorb water differently. If the mixture looks too dry or thick at the 2-hour mark, feel free to stir in a small amount of extra water.
  

• Completion & Storage

  Once the 6–8 hours are up and the mixture is sweet, let it cool down to room temperature. Transfer to clean jars and store.
  
• Refrigerator: Best consumed within 2 weeks.

  Freezer: Can be frozen for up to 3 to 4 weeks.