K-Eldest Daughter Possessed a Childcare Novel

I possessed a childcare novel, in a rather absurd role. ‘The eldest son who resembles the cool-headed duke of the north… is a girl?’ In the original work, he was the duke’s eldest son and heir who adopted the female protagonist, gruff to everyone but affectionate to her as the eldest brother. And now, that was who I had become! “Since Belladi is the elder sister, you should be accommodating, right?” Even our parents raised my younger brother and me differently. “As the heir, I command you, behave and don’t do anything!” My novel counterpart’s brother was ignoring me completely. … well, who cared about being a son or daughter? First, let’s discipline this disrespectful little brother. *** I decided to reclaim what the original eldest had possessed and correct the hierarchy in the house. From loyal servants to the spirit’s treasures, even the heir’s position. And finally, Father returned home with the young original female protagonist. “She will be known as Nesia, the youngest of our family from now on. Come, start call me Dad.” “I’m your brother! Say it quickly!” The now 11-year-old female protagonist was truly lovely and angelic. Of course, I wasn’t interested in her at all. There were plenty of others who admired her besides me. But something felt strange? “Ah…” “Yes, Dad!” “No, brother!” “Sister… ♡” The female protagonist pushed aside my frozen father and younger brother to come to me. I hadn’t done anything for her, so why did she like me?