Risu ni Natte Shimatta Konyakusha ga, Kegirai Shite Ita Hazu no Watashi ni Tasuke wo Motomete Kimashita.

Count Amelia, daughter of the Countess, has been abused by her family and disliked by her fiancé, Cedric, who sees her as unsociable. Amelia lives a life supported by her beloved job as a pharmacist, but one day, someone comes to visit... Cedric, who has been poisoned by someone and turned into a squirrel!? "Please let me stay in this room," Amelia pleads, and so begins her strange cohabitation with her fluffy fiancé (the squirrel)! (Source: Kadokawa, translated)