Kono Naka ni Hitori, Imouto ga Iru!
Abiding by his father's will, Shougo was transferred into Miryuuin Academy where many young girls attend. It appears as though his younger sister, separated from him at birth, also attends this academy, and that she is trying to get closer to him without letting him know who she actually is. At the same time, Shougo becomes popular with the other girls as well.
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