Kazumi wakes with no memory of who she is, only the name people call her by. Found by Umika Misaki and Kaoru Maki, two magical girls she can no longer remember living with, she learns she can transform too and joins their fight against witches in Asunaro City as a member of the Pleiades Saints. As Kazumi searches for her missing past, she starts to realize the people closest to her may not be the allies they claim to be.