This Yellow Koji is produced with 70% milling ration rice (30% is milled off as flour).
Koji (Aspergillus oryzae) is a fungus that is grown on rice during the Sake making process. Koji is grown on rice which breaks down starch in the rice to a more fermentable sugar source. Yeast can then use these sugars during fermentation  to produce sake.
Yellow koji should be used for sake brewing at a koji to grain ratio of 1:5 (20%).