After a freak accident, Grace, the daughter of a Count, realizes she carries memories of a previous life inside her. She realizes that she has been reincarnated into the world of an otome game but she can’t quite believe it. In the game, Grace’s paternal half-sister Mira is the heroine, while Grace herself is the sadistic elder sister,the so-called Villainess who torments her younger sibling. However, with a newfound maturity from her past life memories, upon meeting her sister, her protective instinct as elder sister was awakened. Grace, who suddenly developed a major sister complex, was suddenly inspired by a new thought: “Since Father is a scumbag, the one who protects my sister must be me!” Just like in the game, the evil stepmother and target characters to woo such as the brother-in-law show up, creating challenges and opportunities! To have her cute little sister call her “Big Sister” with respect is Grace’s deepest desire!!!