Sasakia charonda, the Japanese emperor or great purple emperor, is a species of butterfly in the family Nymphalidae.

It is native to Japan (from Hokkaidō to Kyūshū), the Korean Peninsula, China, northern Taiwan and northern Vietnam.

They are common in the upper canopies of forests, only coming down to feed or to find salt sources.

[3][4] S. charonda is the national butterfly of Japan.

This article related to members of the butterfly subfamily Apaturinae is a stub.