Elf no Futagohime: Willan to Arsura

There is a world where humans and elves live together. Elf. The world of their skills and longevity. But one day, humans rose to revolt and a big war ensued. After a long battle, the two countries decided to oppose the war by marrying representatives of each type for peace. Arsura, an elf princess, was chosen as the bride. However, compiling him on his way to human territory, he and Willan, his sister and security guard, were abducted by someone! A bunch of monsters appear! Those who kidnapped a sister. Their boss is Daash, who is half human and half fairy. What refute?