Survive as the Adopted Daughter of a Genius Duke

Read manhwa Survive as the Adopted Daughter of a Genius Duke / 천재 공작가의 양녀로 살아남기
In my past life, I was praising my professor as a graduate student; in my present life, I’m praising my younger brother as an older sister. To survive in the Duke’s household where I was adopted, I absolutely have to get on the good side of Kilian, the male lead of the novel. Fortunately, it’s still a long way before the original novel’s events unfold! Reina strives to survive by diligently flattering, running errands for, and offering snacks to the young male lead Kilian, who will eventually eliminate her in the future. “Sister, you have to marry me too.”
What…? Did I win his favor too well by using my past life’s skills to the fullest? This little chubby kid is proposing. I tried to dismiss it as a child’s prank, “You’ve never been my sister. If anything, you’re a woman to me.” Suddenly, a deep voice echoed. When did he grow up so much? Unaware of the passage of time, Reina, who only thinks about escaping, and the obsessive male lead Kilian, who only cares about his sister, engage in a game of cat and mouse in their romance.