Tensei Akujo no Kuro Rekishi

Synopsis

From Yen Press: Konoha Satou has a dark history. After all, she spent her teen years writing self-indulgent fantasy romance fics-like her Dark History. But since she’s become its most despicable villainess, remembering every last detail is now a matter of life and death. Having avoided the first couple of death flags, Satou’s suddenly left in the dark when a mysterious stranger returns from the Lily Kingdom-a character she doesn’t recall writing in the original script. Although Yomi claims to be her ally, can Satou really trust a character she knows nothing about in such a dangerous world? Vol 1 contains the one-shot *Ghost-seeing School Boys*.

Synopsis & details from MangaUpdates