Kono Naka ni Hitori, Imouto ga Iru!  

この中に1人、妹がいる!, この中に1人、妹がいる!, NakaImo, Who Is "IMOUTO"?, My Little Sister is Among Them!

According to his father's wishes, Shougo was enrolled in an academy that primarily serves young females. It seems like his younger sibling, who was separated from him at birth, also attends this school. She is attempting to draw nearer to him without revealing her true identity. However, Shougo appears to have gained popularity among the other girls as well. Can he successfully balance reuniting with his sister and pursuing a romantic relationship?