<Book Introduction> An ordinary male reader and avid fan of the mega-hit fantasy novel that recorded hundreds of millions of views, 『The 13th Prince Has Returned』. While clicking out of curiosity on a 19+ fanfic of the original work, he woke up possessed by 'Cesare von Valois'—the main villain of the original story and an antagonist who meets a gruesome end of revenge at the hands of the 13th Prince, Leoneld. He thought he could survive this life safely as long as he didn't repeat the mistakes of the original work. "No way... am I an omega?" "...? Yes. Aren't you one of the few noble dominant omegas in the empire?" This place wasn't the original work. It was inside the 19+ omegaverse fanfiction that he had quickly closed while shouting for brain bleach—and of all things, as 'Omega Cesare', who gets pinned down by the 13th Prince. There is only one way to survive. To make Leoneld, who is scheduled to kill him, utterly disgusted so that he stays away altogether. "Your Highness the 13th Prince, wouldn't you like to drop by my bedroom once?" "......" "I'll treat you well." Yet something is strange. This was supposed to make him disgusted, so why is this man getting closer and closer? "Didn't you say you wish for my happiness?" "......" "Then please stay still." And after a single night. A variable not in Cesare's life plan— a 'child'—ends up being created. <Author Introduction> Delvecino 『The Villain Hides His Pregnancy』