Chou!!! - Tensai Hatsumei Reijou no Powerful Ryouchi Kaikaku

Marianne, the second daughter of the Countess of Landfouria, is a prodigy who loves books. Her current problem is that her half-sister is shunning her. (Is this the fate of the second daughter?) However, Marianne's natural cheerfulness gradually melts her sister's stubborn heart. Furthermore, the second prince she meets at the school takes an interest in her positive attitude toward life...?