In Another World, My Sister Stole My Name, Vol. 3 -

As the kingdom's second saint, Ichika has her hands full--with her day-to-day duties, her relationships with two princes, and her elder sister, who has grown far more distant than she remembers. So of course, the king couldn't have picked a better time to send them all on a diplomatic visit to the neighboring country! As Ichika scrambles to study up on magic before the trip, she encounters a young girl named Levie who offers to teach her. But there seems to be more to this mysterious child than meets the eye...Just who is Ichika's strange new tutor? And what other secrets will she uncover as she delves deeper into the world of the mirror?