Elf no Futago-hime: Willan to Arsura

There is a world where humans and elves live together. Elves rule the world because of their intelligence and longevity. But one day, humans rise in rebellion and a big war breaks out. After a long battle, both countries decide to stop the war by a marriage of convenience. Arsura, a princess of elf country, is chosen as a bride. However, when she is on her way to the human territory, she and Willan, her sister and security guard, are kidnapped by someone! While elves and humans push responsibility to each other, a group of monsters appear! It's them who kidnapped elf sisters. Their boss is Darsh, who is half human and half elf. What is his purpose...? Another war breaks out now!