The Day I Woke up as the Sacrificial Princess

Despite carrying royal blood, Bryanna lived outside of the palace for most of her life. Upon returning to the palace, she discovers Lilian, the emperor's illegitimate daughter who successfully charmed the emperor with her "adorableness." In the original novel of this story, when the emperor has to offer the life of one of his daughters to the gods, he decides to sacrifice Lilian instead of Bryanna, but Lilian survives and Bryanna dies at the age of 18. However, now there is a new soul in Bryanna's body, and she is determined to go against the original plot.

(Source: Tappytoon)