After Becoming the Villainess's Brother, I Led My Sister to the Top

Being reborn in the world of a novel isn't scary. What's scary is spending the first sixteen years completely unaware, quietly being a model student and earning scholarships, with the biggest dream of having all your tuition waived so you can enter St. Di Academy as a [special admissions student]. The best school in the country, full of young masters from wealthy families. Most importantly, he wanted to see someone. The little sister he had depended on in the orphanage when they were young had been taken in by a wealthy couple. The pale little girl, eyes brimming with tears, desperately shoved a stupid-looking big rabbit with its front teeth showing into his hands, softly begging her big brother not to forget her. Silly girl. When I grow up, who would even remember you? Thinking about it absentmindedly, Su Ai still accepted the little crybaby's stuffed toy. Now the System was telling him that the little crybaby, the sister who had promised to meet him again when they grew up, was actually the real daughter in a switched-at-birth story, destined to be a cannon-fodder character? Ignored by her parents, humiliated by the fake heroine, despised by everyone in their circle, and eventually becoming an utterly vicious villainess who interfered in the romance between the male and female leads. She'd end up in prison, mistreated there for the rest of her life until she died alone. That was the fate of his sweet little sister, his little crybaby? "Heh. Trash." The young man gave a cruel shark-like smile, making the System tremble. "Exactly! So, Host, complete the mission and break up the male and female leads so your sister can take the heroine's place! Then she won't be bullied." "No." The word slipped from his red lips, cold and clear. The handsome, gentle model student tossed off his coat. "It's getting late... Time to teach those pieces of trash how to behave." System: "???" P.S. This is a danmei story, and the love interest is not the sister. It's a story about a shark-like big brother and his little sister taking on the world together (doge face). Theme: Take control of your fate and protect the people you love.