Omae Imouto ja Nakute Iinazuke Datta no ka yo!?  

You weren't my sister, but my fiancée!?, お前妹じゃなくて許嫁だったのかよ!?

Humanity, love your little sister.I miss the time when her younger sister Kana was fond of me. Takashi Shiina lamented the current days when he was often ignored. One day, his parents cut out a shocking story. Surprisingly, he wasn't his real son... but he was his sister Kana's fiancée!?The definitive version of Reiwa's younger sister manga!