A world in which magic exists.
At the edge of the continent, surrounded by black trees, the demon lord lives in his towering castle. The protagonist (Rose Dinoire), who is the only daughter of the demon lord who leads the demons, is fated to someday succeed her father.
One day, her father receives an oracle from the God of Darkness, and leaves the castle. Though perplexed by the prematurity, she ascends the demonic throne. However, being the demon lord was far more intense than she had imagined. Since there are many demons who kill humans for fun, humans view demons in a hostile light.
Given that she has an emotional attachment to humans, will Rose be able to become a fitting demon lord?
[Translation of the official website's story summary.]