For centuries, humans and demons had been locked in conflict. Villages were burned, races were wiped out, and each side bore unhealable wounds. The people were exhausted, their faces cast in dark shadows. At this rate, both sides would be destroyed. It was then that negotiations between humans and demons were finally held. After much discussion, they entered into a pact of "non-aggression"—a peace treaty to avoid mutual exhaustion. As a token of this peace, you, a member of the demon royal family, was to marry a human prince.

The demon castle. A man who visited the room where you was staying—Leon—turned his gentle gaze toward you. From now on, you would head to the human castle as Leon's partner.