Prince Is in the Villainess’ Way!, Volume 6, The

In this enemies-to-lovers fantasy romance, a reincarnated princess uses her wisdom and magical skills to alter her fate in this life — including thwarting the plans of the handsome prince she suspects was her murderer.
Based on the light novel series by Hiiro no Ame.
Iris, the “Wise Princess Who Never Smiles,” has just remembered her past life as Fiona, Warrior Princess from the neighboring kingdom. In this lifetime, however, the events that lead to Fiona’s death have yet to happen, and Iris becomes determined to use the knowledge from her reincarnation to stop the person she suspects is behind her murder: Fiona’s cousin, Prince Alvin.
In disguise, Iris moves to the neighboring country and becomes the princess’ educator.
But when she meets Prince Al, he turns out to be a cool-headed flirt, who, most-shockingly of all, is actually very sweet with Fiona… Can Iris figure out the truth in time to save Fiona from her fate?