I Failed to Oust the Villain!(2022)

Heungmageul Beorineun De Silpaehaessda

Reborn as the daughter of a count she read about in a novel, Lady Valeta knows the story ends in tragedy at the hands of her lowly house pet, Reinhart. Having never wanted him in the first place, Valeta tries but fails to oust him from her house. But when Reinhart’s powerful magic is awakened one day, he kills all those around her, and it is now Valeta who is at his mercy. Though the tables have turned, Reinhart can't shake his attachment for Valeta. He lets her live, but only within his grasp.

(Source: Tapas)

Note: The side stories are rated R19.