The Prince's Favorite Is the Villainess.

One day, an office worker reincarnates into the world of her favorite otome game. Unfortunately, however, she has become the game's villainess, Diana. On top of that, Prince Sirius, supposedly the protagonist's primary target, is targeting her instead. To avoid a Bad End, she needs the prince to hate her. So she tries to seduce him, who supposedly admires purity. However, instead of being disgusted, the prince looks at her lustfully.