You Will Be Mine, Hero. I Refuse!

For 15 years, a war has raged between the humans and demons. The humans' greatest warrior, Hero, heads to the castle of the Demon King, leader of the demons, to end the war. To his surprise, the "Demon King" is actually a queen and she has been waiting to meet Hero in person and wishes to talk with him instead. As they talk, she reveals the war has actually benefited both sides as their races have put aside their differences to fight against a common enemy and improved the economy.