ワガママ先生は僕の妹？ ～ウブなアイツがＨな小説なんて…～

By chance, I noticed that my younger sister Kana's laptop was still open, so I casually peeked at the screen to close it.
What was displayed on the screen was an erotic novel.
And the theme was "Brother and Sister." Confused, I scrolled through the text...and then I noticed something strange. This wasn't something she was just reading, it was something Kana had written. Having discovered my sister's secret, I tried to apologize to Kana, but...