Daiginjo-shu

Thoroughly wash the highly polished sake brewing rice until the water runs clear. Soak the washed highly polished sake brewing rice in pure soft water for a precise duration, typically 30-60 minutes, depending on the rice and desired water absorption. Drain the highly polished sake brewing rice completely.

Steam the drained highly polished sake brewing rice in a large steamer for approximately 40-60 minutes until it is firm on the outside and soft on the inside. Cool the steamed highly polished sake brewing rice to around 30-35°C.

Take a portion of the cooled steamed highly polished sake brewing rice (about 1000 grams) and evenly sprinkle the koji mold spores over it. Mix thoroughly. Spread the inoculated steamed highly polished sake brewing rice in a shallow tray and maintain a warm, humid environment (around 30°C and 70-80% humidity) for 36-48 hours, turning and breaking up the clumps every few hours to ensure even mold growth. This creates the koji rice.