The root portions of mountain-grown 'kuzu' arrowroots are washed in the copious and pristine waters of Kumagawa and then made into starch powder. When dissolved in hot water it thickens into a paste. Cakes and drinks using kuzu starch powder are famous. Kuzu cake made of sweetly cooked red beans wrapped in a kuzu paste and chilled is especially delicious in summer. Kuzu drinks make a warm beverage in the cold of winter.