I'm the Villainess, So I'm Taming the Final Boss, Vol. 1 (Manga)

When Aileen, the Duke's daughter, regains her memories of her past life, she realizes she's barreling toward ruin at full speed. Searching for any way out of her hopeless situation, the method she chooses is to capture the heart of the last boss--the Demon Lord Claude!
Avoid the at all costs! bad ending. When her fianc� breaks up with her in front of the entire student body, noblewoman Aileen d'Autriche is devastated--or she would have been, if that wasn't also the exact moment memories of her past life came crashing back! Turns out, she's been reborn as the villainess of a dating sim...and according to the story, she's slated to die at the hands of the demon king in three months! But Aileen's already got a plan: Step one, get Demon King Claude to fall in love with her. Step two, live!
Avoid the at all costs! bad ending. When her fianc� breaks up with her in front of the entire student body, noblewoman Aileen d'Autriche is devastated--or she would have been, if that wasn't also the exact moment memories of her past life came crashing back! Turns out, she's been reborn as the villainess of a dating sim...and according to the story, she's slated to die at the hands of the demon king in three months! But Aileen's already got a plan: Step one, get Demon King Claude to fall in love with her. Step two, live!