After a long and treacherous journey, our Hero finally arrives at the Dark Lady's castle only to find himself being asked for help. The Hero explains how the war that the demons have brought upon the humans have killed thousands and put more in misery. The queen of demons however argues that this war has made the human society band together as one and showed empirical evidence how it has increased population, increased production, boosted economy and improved society overall. Furthermore, she explains to the Hero that ending this war will result in a civil war that will produce more bloodshed than there ever was. The Hero, convinced that the only way to bring peace, relatively speaking, is to join forces with the Dark Lady, agrees to help with her plans!

(Source: MU)

The story is set in a world embroiled by war between Humans and Demons. The Humans' greatest hero invades the Demon Queen's castle determined to vanquish her. However, instead of fighting back, the Queen proposes an alliance with the Hero. She explains how a sudden end to the war can bring further chaos to the world as the Humans once united to stand against their common enemies would eventually begin fighting among themselves, with similar issues already occurring at the Demon Realm. Convinced by her words, the Hero joins forces with the Queen and together they execute a plan to bring prosperity and a lasting peace to both Humans and Demons alike.

Source: Wikipedia