Oni-san no Tokoro e Mairimashita

Synopsis

A girl was given to an oni as a sacrifice, however, he had merely asked for a servant. Since the oni in question is against child labour and she has no place to go, he decides to make her his temporary "wife" in the name. So the young girl and the cheerful oni begin their warm (married?) life together. (Source: MangaUpdates) Originally published as doujin web manga on the author Pixiv and Twitter until picked up by Square Enix and Pixiv.