So My Sister Is a Sadistic Heroine? !

In order to save a little girl, Bai Ruyue died. After her death, she discovered that her world was actually a book? ! Her sister is the heroine of this book, and she is a cannon fodder living in the heroine's memories... Well, it doesn't matter. Her sister is so cute and it's natural for the heroine to do so. Then, she discovered that her sister was tortured to death by the male protagonist in it, and even fell in love with him as if she was insane. It is unbearable! So, Bai Ruyue, who had been reborn, rolled up her sleeves to protect her sister and never let that scumbag get close to her!