Nagatanien Nagatanien’s Iga-Mono line of handmade cookware comes from Iga (Mie Prefecture,). Many consider Iga ware the epitome of Japanese ceramics. The clay is most well-known for its ability to withstand extremely high heat and weather rapid changes in temperature without cracking. The strength of Iga ware is due to the special clay that comes from earth layers that were once the bottom of Lake Biwa. From years of aquatic life, the clay contains large amounts of organic matter which turn into air pockets when the clay is fired. The air pockets allow the clay to breathe as well as retain heat better.