Kanojo ga Koushaku-tei ni Itta Riyuu

When, after her sudden death, Rinko Hanasaki is reborn as Raeliana McMillan, she is not sure whether to curse her luck. Raeliana was a minor character in a novel Rinko read, and as the eldest daughter of a nouveau-riche baron, she led a carefree life until her unfortunate demise at the hands of her fiancé, Lord Francis Brooks. To avoid her destined fate, Raeliana is determined to end her engagement with Francis.

However, when Francis refuses to break things off, Raeliana decides to seek help from someone of higher standing and approaches Duke Noah Wynknight—the novel's male protagonist. Using her knowledge of the plot, Raeliana captures the duke's interest by proposing a deal: she will not expose his secrets if Noah agrees to act as her fiancé. Little does she know that getting involved with a duke who only shows his true colors around her may lead to more than she bargained for.