In Doumori, an imbalance of spiritual forces threatens to plunge the small city into complete chaos. Thankfully, for the students of Doumori Elementary School, new teacher and exorcist Meisuke "Nube" Nueno is determined to prevent the malignant spirits—known as youkai—from accomplishing their evil deeds. The first student who catches Nube's attention is transfer student Hiroshi Tateno, who displays inexplicable outbursts of anger, often lashing out at his classmates. When they find out that Hiroshi is possessed by a youkai, Nube manages to free his student thanks to the demonic power sealed in his left hand. However, a youkai hiding behind the appearance of doctor Kyousuke Tamano bursts onto the scene and quickly abducts Hiroshi. Helped by his student Kyouko Inaba and his expertise in the occult, Nube quickly uncovers Kyousuke's sinister plans. Rushing to Hiroshi's rescue, Nube will show once more that he will stop at nothing to protect his beloved students against all supernatural threats.

Nobody asked to be a cat! After dying in a fight against the forces of evil, a knight is shocked to discover that instead of being reborn as a hero of humanity, he starts his new life as a behemoth-one of the most powerful monsters in the world! The only problem is that a baby behemoth looks an awful lot like...an adorable house cat?! Things grow even more confusing when a beautiful elf adventurer rescues him from the brink of death rather than finishing him off. This house-cat-slash-knight's baffling journey is just getting started...

High school first year Yuu Yuutani has always been a good girl, following the rules, helping out around her house, and generally going through life unnoticed. From afar, she reveres her upperclassman and the school's Public Decency Officer, Atori Mizutori, and desperately wants her attention. When she realizes that the best way to get Atori to notice her is to be a delinquent, she begins to dress differently: she dyes parts of her hair a bright red, wears clips on her ears to resemble piercings, and attaches jumbo erasers to her shoes to give them thicker soles. Despite Yuu's best efforts and even with the advice of her "natural born delinquent" friend Suzu Suzukaze, all of her plans to be a bad girl go awry. Still, Yuu manages to befriend Atori and pledges to spend as much time as possible together, not knowing there are others vying for Atori's attention. In the process, Yuu has also gained the attention of the school's self-proclaimed idol, Rura Ruriha, filling her once-invisible life with more attention than she may be able to handle.

Unlike his twin brother, Yukio, Rin Okumura never wished to know about their parents and the circumstances surrounding his own birth. Yet the master of time, Mephisto Pheles, gives Rin a key that transports him 40 years into the past when his late mother, Yuri Frederick Egin, was merely a child. With Mephisto's guidance, Rin leaps through the years of Yuri's childhood and her adolescence as an exorcist-in-training. Early on, Yuri meets Shirou Fujimoto, Rin and Yukio's adoptive father. As Rin follows Yuri and Shirou's lives, he witnesses firsthand the initial appearances of Satan, his true father, and the horrors unfolding at the True Cross Order's special Section 13. Yuri's unique connection to Satan eventually leads Rin to the truth behind the most horrific event in exorcist history and the day he and Yukio were born—the Blue Night.