Read My Fair Maid Manga:
Sandy, an adorable maid, whose hobby is cleaning, becomes a fianc of the young master, Killian, who is a ladies' man with a snippy attitude. One day, when it was thundering, Sandy was possessed by Alexandra, the prettiest socialite. She becomes a fianc of Killian, the young master of the highest noble family, who has been mesmerized by Alexandra! However, they are their worst enemies. To go back to her body, sh more.. e pretends to be Alexandra, hiding her true intentions.