The Demon King: Let's Make the Hero Our Bride

There was a Demon King in the world. The King of Athena Kingdom, one of two great nations, recruits a hero and orders the subjugation of the Demon King. Sensing the movements of the hero party, the Demon King was somewhat angry. Despite ruling his country so earnestly, why must he be defeated? It made no sense. Moreover, there were questions about the hero and the party composition. Why is the hero a colonel in the Athena Royal Army? Why isn't the top brass coming? And why is everyone except the hero female? A harem? —How ridiculous. So the Demon King made a decision. When the hero arrives, he would absolutely harass them. From the meeting between the hero, setting out in high spirits to subjugate the Demon King, and the Demon King, waiting with nothing but grievances, a fate (of love) begins.