My Little Sister is among them!

Delve into the world of Kono Naka ni Hitori, Imouto ga Iru!, a captivating light novel that explores the story of Mikadono Shōgo, an heir to a business empire who must fulfill his father's dying wish by finding a suitable marriage partner before graduating high school. Amidst the backdrop of Miryuuin Academy, Shōgo's life takes a twist when a girl claims to be his sister but conceals her true identity. The novel blends elements of comedy, ecchi, harem, romance, school life, and seinen genres, catering to fans of adapted anime and manga, as well as themes of amnesia, incest, and sibling relationships.