Maoyuu Maou Yuusha

Since the start of the conflict between mankind and demons, fifteen years have passed. The Hero abandons his allies to forge ahead fast towards the Demon Queen's castle after growing impatient with their plodding entry into the Demon Realm. The Hero is shocked to learn the Demon Queen is not only a woman of unrivaled beauty, but she also needs the Hero's assistance when he arrives at the royal residence. The Hero, perplexed by this sudden turn of events, refuses to join forces with his adversary, arguing that the battle the demons have fought is dividing the Southern Nations. The Demon Queen replies, pointing to facts to corroborate her statements, and asserts that the conflict has not only brought humanity together but also wealth and prosperity. She also says that if the war ended, the Central Nations' aid to the Southern Nations — including food — would stop, leaving hundreds of millions to starve. Fortunately, she presents the Hero with a plan to put an end to the war while giving the Southern Nations and the rest of the world hope, albeit she will need his help to make this happen. The Hero finally gives in and joins his now-ex-enemy on her quest. When they left into the human world, they made a commitment to stick together in good times and bad.