Akuyaku Reijou no Okiniiri Ouji... Jama

Iris, the "Wise Princess Who Never Laughs," has her memories of her reincarnation rewound and discovers that Fiona, the princess of a neighboring kingdom, is her former life. Iris realizes that Fiona is in trouble because of Prince Alvin's betrayal. She goes to the neighboring country as the princess's educator to save Fiona, but...?

She is a prince, but she can't sense the subtleties of a prince!