Because this is the height of the brewing season. Sake kasu has long been used in Japanese cuisine, and imparts a unique flavor and touch. Below are a few tried and true examples of cooking with kasu. There are countless recipes and variations. Salmon is then added, with miso or salt added for flavoring.
Some recipes call for the reassuring addition of a dash of sake as well.
In his book An Insiders's Guide to Sake , Philip Harper presents a pork kasu jiru recipe from his wife Yasuko. Although salmon kasu jiru is more common, I personally prefer this version, which is simple to make. That alone is reason enough to buy his book. Kasu Amazake Break kasu up into small pieces and mix it with water to a pleasing consistency, similar to a soup. Heat it up and add sugar to taste, and a dash of ginger.