When Japan entered the Iron & Bronze Age, the Yayoi people started making many bronze objects in the Korean and Chinese tradition. However, they soon began to produce the objects in unique Japanese forms. One strikingly unique bronze object indigenous to Japan is the tomoe bronze cog-wheel ornament. It resembles the ninja shuriken weapon but was probably copied from the shape of the Harpago chiragra seashell bracelet (right). These tomoe or shuriken like objects were used to decorate shields and other objects. These ornaments were found in Kyushu, Shikoku and the Kinai region. 

Photographed with permission at the Tokyo National Museum