Isekai Shimai to Hajimeru Ryouchi Keiei: Konyakusha ga Zense no Imouto de Nigerarenai (Light Novel)

“I’m absolutely serious. I want to marry you, Brother.” In the struggle against his brother to inherit the county, Allen tries to bring his stepsister, Chris onto his side. At the same time, he thought of conducting a marriage of convenience with the Marquis’ daughter, but… “Long time no see, Brother.” Who would have thought that she would be his sister from his past life!? “I’ll make sure to bear your child this time.” Should he consider himself lucky? Or is this a crime? What will be his fate as the ultimate choice approaches…!