In a mixing bowl, combine malted barley flour and water and mix well. Let the mixture sit at room temperature for 2 hours.
After that, carefully strain the clear mixture that floated on top through a fine sieve. Discard the leftover barley flour from the bottom of the mixing bowl. (See notes for more useful info)
Add cooked rice and sugar to your rice cooker. Carefully pour the strain mixture into the cooker. Then, set it on a warm setting and let the liquid ferment for 4-5 hours.
The drink is ready when rice is floating over the liquid. Then, strain the fermented liquid through a fine sieve.
Keep the rice separate in cold water and store it in the refrigerator. Return the strained fermented liquid to a stovetop and add 1-3 cups of water (it'll depend on the level of sweetness that you prefer your drink to be).
Bring the fermented rice juice to a boil and cook for 5 minutes to stop the fermentation process (Adjust your stovetop heat accordingly to prevent the liquid from overflowing). Constantly skim the foam that formed on top of the surface.
Let the drink cool down (approximately 20 minutes) before straining it through a fine sieve line with a couple of coffee filters to achieve the most clearness of the liquid.
Serve the drink with fermented brown rice, shaved ice or ice cube, and pine nuts.