Yona of the Dawn. Volume 4: Mizuho Kusanagi

A red-haired princess loses her family and her kingdom… Now she must rise and fight for her throne!
Princess Yona lives an ideal life as the only princess of her kingdom. Doted on by her father, the king, and protected by her faithful guard Hak, she cherishes the time spent with the man she loves, Su-won. But everything changes on her 16th birthday when tragedy strikes her family!
While on a quest to find the Four Legendary Dragon Warriors, Yona and her friends meet Gija, the White Dragon. Gija uses his power to detect the other Dragons, but locating the Blue Dragon proves to be more difficult than expected, and the group runs into a string of disasters!