I'm in Love with the Villainess (Manga) Vol. 8 by Aonoshimo

In order to ensure her child, Yu, had the right to ascend the throne, Queen Riche used magic to change Yu's gender from a girl to a boy as a baby. Having learned this, Rae asks her friend Misha for help setting things right. But before Rae and Claire can figure out how to reverse the spell, they must deal with a mysterious criminal organisation that's been kidnapping students!
Binding: Paperback / softback