Tokoname Yaki is a form of ceramic pottery that is produced in the area around the city of Tokoname in Aichi prefecture. This traditional craft comes from one of the Six Ancient Kilns of Japan. Along with Bizen, Tamba, Echizen, Seto, and Shigaraki, Tokoname is one of the most outstanding Japanese kilns with traditions that remain even today. Tokoname ware was created in the latter part of the Heian period (794-1185), making it an incredibly ancient form of porcelain. Its unique color is caused by the iron which makes the clay turn red after baking. This is called shudei (the unglazed reddish brown pottery). Small iron teapots are especially favored today because the iron is said to smoothen the bitterness and astringency of tea. Other techniques are yoriko tsukuri which is used when producing large items.