Ookami wa Koi ni Naku

Deep in the mountains lies a land of people who live in harmony with wolves. Among them, those who are born with white hair are called "white deers," said to have descended from the white deer of their legends. Sara, a "white" deer raised to marry into the royal family, has always been infatuated with Prince Alaxy, well aware that the two will become "mates." However, it seems that the one Prince Alaxy has always loved is her twin brother, Nara. She tells herself that she does not mind being even his substitute. This is but one of multiple stories taking place in the world of this mystical kingdom.

(Source: Frontier Works)