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

Synopsis

The one who saved the oppressed young lady was... a squirrel. Amelia, the daughter of an earl, was abused by her family and hated by her fiancé Cedric, who considered her unfriendly.But that didn't bother her. One day, while she was finding comfort in her beloved job as a pharmacist, someone came to visit her...Cedric, who had been poisoned by someone and turned into a squirrel!? "Please let me stay in this room," he demanded her, and so began this strange cohabitation with her nagging, fluffy fiancé (the squirrel). (Source: Kadokawa, translated)