My Next Life as a Villainess: All Routes Lead to Doom! (Manga) Vol. 8

A RIVAL APPEARS! Katarina and her friends mount a daring rescue mission to save Keith from the clutches of dark magic users, but in the end, they're still expected back at school, where graduation is just around the corner. Having dodged every doom flag, Katarina is tempted to let her guard down--but she never expected the appearance of a new rival, Marcia. Not only is Marcia in love with Prince Jeord, she's one of his past fiancée candidates, and she wants Katarina out of the picture once and for all!