Black Crystal

The Black Crystal King is the main villain of Fushigiboshi no Futagohime series.

Information
It is the original source for all the powers of darkness. It also controls what Bright does, forcing him to use the Prominence when someone disobeys him. Although the Black Crystal does not walk by itself, it can expand rapidly. The fuel for it are the people's sadness. However, that Black Crystal King was an imposter, while the real one only appears in the Gyu! series.