Cinderella? Not while I'm here!

After accidentally discovering the secret hiding place of her older sister, the little girl suffered a great shock that will greatly affect her current and future life. —I will protect my sister! And I won't let anyone touch the big brother! Knowledge is power, and money moves the world! Born in a noble family, money is not a problem, the knowledge you want can be acquired just by asking. Loving parents, a perfect brother and a lovely sister; Calling her the little princess in her family wouldn't be wrong. However one day suddenly a completely unknown child appeared. Too bright... Is this child supposed to live with us? —You... look like a doll. Eh? What? What the hell was that?