You can't buy the fermented grains in the supermarket, because they have been sterilized and have no fermentation ability.

Wine _, generally writing wine qu. After intense cooking, the conidia of Aspergillus are transplanted into the white rice, and then the temperature is kept, and hyphae will flourish on the rice grains, which is called koji. The amylase produced by Aspergillus will saccharify the starch in rice, so it has been used as raw sugar together with malt since ancient times to make wine, sweet wine and soybean paste. Those who use wheat instead of rice are called wheat qu.