Sterilise a bucket or large pot.

Cook steamed rice with less water than usual. About 750 ml for 750g rice. This water is not included in the ingredient.

Put water and streamed rice in the bucket as soon as it cooked. Stir it gently.

Put Kouji and stir it.

Put yeast and yogurt. Stir it gently. You can use yeast for baking or yeast for wines

Cover it but do not seal because it generates gas (co2).

Wait 3 days in 15-20 degrees. Cane be 2 days in Summer time and 4 - 5 days in Winter time. Stir 1 or 2 times a day.

Strain through steainer or coase texture cloth to make it smooth. This process produce fair amount Sakekasu, the left over bits from the sake making process. It can be used for cooking.

Leave it at least a day in the fridge and enjoy.

You can keep it for a couple of weeks in the fridge but do not seal it in a glass as it still produces gas even the fridge. You can keep it longer if you heat it to 60-70 degees (no higher than 70) but I'm sure it will gone in a two weeks.