The Kuji region is the largest producer of amber in Japan. Amber is a type of fossil that is formed when resin from trees that flourished on the ground tens to hundreds of millions of years ago is buried in soil and fossilized. Kuji amber is approximately 90 million years old and is thought to have originated from the South Seas cedar (scientific name: Araucaria), making it the oldest amber used commercially. It is mainly used for jewelry such as accessories and crafts.