Ryuu Ou no Kagehime, Volume 1 (Shadow Princess of Dragon King)
Ryuu Ou no Kagehime or Shadow Princess of Dragon King is a shojo manga by Akira Oosora.
Ryuu Ou no Kagehime takes place in a world where dragons have the power to call forth the elements. The people of Mikage are dependent on the water dragon who brings rain to the village when it suffers from drought.
One day as the water dragon is flying over Mikage village, it suddenly goes berserk. Its rain floods the village and all but one of its residents drown. That survivor is Kohaku who dedicates the rest of her life to getting revenge. For her, revenge means killing Miaki, the son of the emperor and the only one who can control the water dragon.
This listing is for Volume 1 in Japanese.