Me, the Invincible Demon King and the Girls of the Human Kingdom

I unexpectedly traveled to a parallel world and became a Max-Leveled Demon Lord. And now, standing before me is a human girl. Girl: "The princess of our human kingdom has been captured by Orcs. I hope you can go and rescue her." Me: "Demons and humans are hostile races, I refuse." Girl: "As long as you can save the princess, I'll do whatever you ask." Me: "......." Several hours later, I saved the princess. Princess: "Thank you so much for saving me. To repay you, please marry me." Original Novel Official English