Storing awamori in a "Kame" or specially made clay jars ages the awamori three times as fast than wooden barrels. Research indicates, the calcium and magnesium in the clay are the first to have an effect. After two years, iron kicks in to bring out a sweetness. The manganese comes into play and enhances the aroma. After three years in a kame, Okinawans call this "Kusu," or old liquor.