We would recommend playing the demo before purchasing any game, regardless. That being said, the MC is written as the same person, only from a different universe where she is sent into the novel a few months earlier than in Duke’s game, resulting in her ‘becoming’ a different novel character. There will be an option to remain platonic with Roy and enter Duke’s branch instead, BUT as mentioned on the main page, since Duke is not the protagonist in this installment, his solo content will be sparse.