Sasakia charonda, commonly known as the Japanese emperor or the great purple emperor, is a species of butterflies in the family Nymphalidae. It is native to Japan (from Hokkaidō to Kyūshū), the Korean Peninsula, China, Northern Taiwan, Northern Vietnam. Their wingspans average at 50 mm (2.0 in) for males, and 65 mm (2.6 in) for females. They are common in the upper canopies of forests, only coming down to feed or to find salt sources. The larvae of the species feed on hackberries, like Celtis jessoensis, Celtis japonica, and Celtis sinensis.