After Being Gutted Eighteen Times, the Cannon-Fodder Princess Turns Dark Online

[Transmigrate into a book + mind-reading + no romance] My plot is a bloody mess, so I go completely wild and make history. As a modern person, I accepted transmigrating into a book pretty quickly. But why did I have to become a cannon-fodder princess in a brainless, outrageously melodramatic story? After being killed for the eighteenth time, Mu Wanju was reborn again. This time, the six-year-old her had a late-arriving System, and instantly turned ruthless. A dagger in her left hand, poison in her right, she decided to solve the problem at its source! Want to stay alive? Strike first! Consort Rui framed my mother for poisoning someone, and my scumbag father believed her. Kill him! My second brother has a hopeless case of love-brain. He got his leg crippled saving the heroine, and dragged me into it too. Cripple him first! My fifth imperial sister could have married anyone, but she chose some mere top scorer in the imperial examinations. Then that scumbag used her and tossed her aside, and she was abused to death by beggars? My eldest and sixth brothers were manipulated into turning against each other, and ended up dead or crippled. I got dragged into that too. Even my fourth brother, who was manipulated and badly injured, ended up dying of rage after being falsely accused of usurping the throne, and I got dragged into that as well... I get it now. Mu Wanju had already watched her unreliable brothers and sisters die once. She decided to turn ruthless and kill everyone who stood in the way of her survival. If she couldn't live, then no one else would either. Little did she know that everyone who heard her thoughts would run off in tears to ask for help. “Father, save us! Little Sister has gone dark again!” [Ding! Congratulations, Host. You have officially unlocked the main quest: unite the realm and bring everlasting prosperity.] Looking at her seven-year-old self, Mu Wanju snapped and yelled, “System, what is wrong with you? I'm still a child!”