I'm Secretly the Father of the Yandere Villainess's Daughter

**"I will make you submit completely... until every part of your existence belongs to me."** Cain Oster thought his new life would be perfect. After being reincarnated into the world of his favorite novel, he became the young master of the powerful Oster Dukedom. With his wealth, status, and the mysterious **Sign-In System** that allowed him to grow stronger by checking into different locations, Cain believed he had everything under control. Especially after one unforgettable night with a beautiful woman he met by chance. He thought it was just a harmless encounter. He was wrong. One day, the infamous **Yandere Villainess** appeared at his door with a shocking request. "Young Master Cain... I know this is shameless, but I must ask you to take care of my child until I finish my revenge against the man who betrayed me." Cain was speechless. The woman standing before him was none other than **Lucy Montgrad**—the final villainess of the novel, a terrifying woman known for her overwhelming power and obsessive personality. And the child she brought with her... Looked exactly like him. Cain never expected that one random night would come back to change his entire life. Now, while Lucy hunts down the person who abandoned her, Cain finds himself raising a daughter born from the most dangerous woman in the story. A daughter who inherited her mother's obsession... But was still unbelievably adorable. Cain only has one problem: Lucy must never discover the truth. Because if the most powerful villainess in the world finds out that Cain is the father of her child... His peaceful life may disappear forever. **Tags:** * Overpowered Male Lead * Overpowered Female Lead * Reincarnation * Sign-In System * Powerful Villainess * Fantasy Romance * Raising a Daughter