"Sister-in-law, I'm quitting being a villainess."

I was reborn as the stepbrother of the villainess in an otome game. Whether my stepsister's engagement gets broken off or she gets condemned, I don't care. Along with my stepsister's condemnation, the Duke's house's misconduct also gets exposed and they fall into ruin. So what? Bring on the downfall! Since I've been reborn in a world where magic and monsters exist, there's only one path forward—becoming an adventurer. I'll forget about the otome game and live freely on my own terms. 【This is the story before the game begins.】