My Stepmother and Stepsisters Aren't Wicked manga volume 3 features story and art by Otsuji.

Miya, an illegitimate child of the Kounokura family, continues her days living with her less-than-wicked stepmother and stepsisters. And now that her precocious cousin Yaeko has integrated herself into Miya’s daily routine, her family ties just keep on growing. But just as she’s starting to get the hang of things, a new challenge appears...in the form of an academic exam! Will Miya make the grade? And just who are these scary society ladies calling themselves the Four Heavenly Queens? Find out in the third volume of this fairytale turned on its head!