The koji breaks down the polysaccharides in the rice to disarracharies giving it a very sweet taste. Try to avoid drinking too much of the amasake drinks made with almonds or nuts as they can be hard on the digestion. Stevia is just one of the more popular ones. There are other herbs which are sweet and safe for everyone which will be added in the future as they become generally available. It is a little expensive to use in large amounts.
Raw sugar is often white sugar with coloring.
Please don't become a guinea pig for another poorly-tested toxic sweetener only to find out years from now that it contributed to the destruction of your health.