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.

S. charonda is the national butterfly of Japan, where it is known as 大紫 or オオムラサキ (oh-murasaki, "great purple"). Its Chinese name is 大紫蛺蝶(Traditional Chinese) and Korean name is 왕오색나비, which means 'king five-coloured butterfly'.


source - Wikipedia