Rei's father was a master swordsman and he left her a single keepsake: a wooden sword. His abilities live on within her, and she regularly polishes them to put an end to the demons that have long stood against her family..
Having received a lead on the demons she pursues, Rei soon meets a certain girl at the school she transfers to This girl, Setsuna Shindo, turns out to be an exorcist, and also an enemy of the very same demons that Rei hunts.4
The two have a very different approach to hunting demons, and find themselves generally at odds. Despite this, during their battles, they cannot help but acknowledge each other's respective skills, and eventually grow closer.
Through interactions with Setsuna's older sister Yuka, her childhood friend Toma, and Setsuna herself, Rei finds herself opening up little by little.