In a medium pot, mix together malt barley flour and water. Let the mixture sit for 2 hours.
After that, carefully strain the clear liquid that separated on top through a fine sieve lined with cheese cloth or paper towel to another pot. Discard the left over malt barley that sunk to the bottom.
Let the strained liquid sit for another 30 minutes if it still carries over some of the white impurities. The clearer the liquid, the better the final drink is gonna be. Strain one more time to eliminate these sediments.
Spread 1 cup of cooked rice evenly in your rice cooker. Pour the strained liquid and sugar very slowly in the cooker. Set rice cooker to warm setting and let the mixture fermented for 4 to 5 hours. If you don’t have rice cooker, you can do this in the oven on the lowest temperature setting. After 4 hours, open the lid and check whether the rice is fermented, you should see few rice grains float of top of the liquid. If not, let it continue the process for another hour.
After the mixture done with the fermented process, strain it one more time. Keep the rice separated in cold water, store in refrigerator.
In another pot, bring the fermented rice liquid to boil, add more water. If you want your juice looks a little bit yellow (like mine), add 1 cup. However, if you like your juice looks more white, add 2-3 cups of water (adjust sweetness with sugar if needed). Constantly skim the foam that formed on top of the surface. Boil the rice juice for 5 more minutes to stop the fermented process.
Store rice juice in tight container and refrigerate. Rice juice tastes best with shaved ice or half frozen and cold fermented rice, pine nuts (optional). Enjoy!