I Shall Become The Best Villainess Ever!

One day I gain my memories of my past life and... Hm? My adorable younger sister is the heroine of a fantasy novel? And I, the jealous villainess must make her life hell, so that one day she can be saved by her princes? How can I bring myself to hurt my fluffy bunny? But... I must. For her happy ending, I will brave t...