Maoyū Maō Yūsha, is set in a medieval world wherein, there is an ongoing war between humans and demons. In order to settle the war the humans sent out a hero that would kill the demon king.
In the demon king's castle, it turns out that the king was actually a girl and that she is madly inlove with the hero and wishes for him to sign a pack of agreement and cooperate with her to tactically stop the war without letting anyone die. With her strong persuasion, the hero agreed and thus the start of their plan to help both races and end the war in a peaceful way there is.
