Kanojo ga Koushaku-tei ni Itta Riyuu (Anime) Wiki

Living inside a fairy tale may sound like a dream, but for this heroine, it’s more of a nightmare. After her mysterious death, Rinko is reborn as Raeliana—a loved and wealthy character in a novel. But she knows the ending: her murder at the hands of her fiancé. So, she hatches a plan to stay alive, one that involves a devilish duke and a phony engagement. Can she rewrite her story?

Source: Crunchyroll