The general premise is right there in the title. Our protagonist reincarnates into the world of game his sister had blackmailed him to play for her. Which is a reasonable explanation to have someone who would not be the target audience of such a game play through it. The description of the game from the prologue also allows the world to be nonsensical and inconsistent in various places due to it being based on a silly game and thus still fit the story. The one part that doesn't really fit for me is the protagonists insistance on following through with the 'logic' of the otome game world when it comes to his position and what's expected of him with finding a marriage partner. He's perfectly willing and even hoping to throw away his title to avoid having to marry some harpy, but when that fails he goes right back into the mindset of having to find a wife. There is an explanation given, but considering Leon's ownership of Luxion he hardly has any reason to be concerned. Aside from that it's a rather enjoyable story overall. Leon just can't stay out of trouble.