Okitsune-sama no Wakeari Yome

Once every 100 years, a sacrifice must be made to the fox spirit - that is the village code. Miya, a young man in the village, announces that he will take the place of his sister and go to the fox spirit himself. As the fox spirit infuses Miya with his essence, he is slowly transformed into a woman fit to be the fox's bride. And the "okitsune-sama," the object the villagers' awe and fear, turns out to be ever so kind…

(Source: Bebe, translated)

Note: Chapter count includes one bonus chapter.