The Sake Service Institute created four classifications for sake based on aroma and flavor. One of these classifications, Juku-shu, or aged sake, has both a robust flavor and aroma. These sakes typically exhibit funky notes with lots of depth. To be considered juku-shu, the sake must have been aged for a significant period of time, making them fairly hard to come by. Try pairing juku-shu with aged cheeses and foie gras.