Onechan to Issho Ni Isekai Wo Shihai Shite Shiawasena Katei Wo Kizukimasho? (MF Bunko J) [Light Novel]

[Machine Translation] Will you go to another world and marry me? I was in a panic at the sudden appearance of a beautiful, unknown girl, but it turns out that she was not proposing to me herself. It seems that she is a messenger, and that my missing sister has actually been reincarnated in another world, and has come to deliver her message. She came to tell me that my missing sister had actually been reincarnated in another world. Then let's get married in another world. I ruled the city for you. Apparently, she went to the other world to make her brother's marriage possible, and she was so muscular that she changed the rules of the city. -Yes, my sister is "apparently" the strongest ruler in the other world.

「異世界に行って結婚してくれませんか?」突然現れた名も知らぬ美少女のセリフにあわてふためく俺だったが、どうやら彼女自身のプロポーズではないという。彼女は使者であり、行方不明になっていた俺の姉が、実は異世界に転生していて、そのメッセージを伝えに来たらしく―。「お姉ちゃんのこと好き?なら、異世界で結婚しましょう?あなたのために都市を支配したんだから」...どうやら弟との結婚を可能にするために異世界に行き、都市のルールを変えるほどの無双をしていたみたいである。―そう、俺の姉は異世界最強の支配者『らしい』。