On her 16th birthday, Himari Momochi receives a letter stating she has inherited a mansion called the "Momochi House." Having been raised in an orphanage, this mansion is the only thing left of her real family, so Himari pays no mind to the rumors that it may be haunted. Upon entering it, she meets Aoi Nanamori and his companions, Ise and Yukari, who all seem to be squatting in her new home. Although they warn her to leave the house, Himari vows to be the one to make them leave instead. But soon, she is attacked by youkai and finds out that the house sits in the space between the world of the living and the spirit realm. Even more surprising, Aoi was chosen to be the guardian of the house—a position originally meant for Himari. But this great power came with an awful price: Aoi can never leave the mansion, and his existence in the human world has been erased. Ignoring his pleas for her to leave the mansion, Himari promises to help Aoi break the housebound curse as she begins living under the same roof as him.

At True Cross Academy, Rin Okumura unknowingly comes across the first signs that something is amiss; ordinary people have been gaining the ability to perceive the invisible creatures that roam the human realm, Assiah. While Rin sees this as an opportunity to make a new friend, his twin brother, Yukio, is more burdened than ever. Swamped with his education, exorcist duties, and teaching position, Yukio has remained silent about his awakened powers, unable to understand their scale or significance. While Rin and his friends prepare for the annual Exorcist Certification Exam, the True Cross Order has uncovered the first artificial gate to the demonic realm of Gehenna. Witnessing its size and the advanced technology that made it possible, the exorcists realize they are now dealing with the Illuminati, an extremely wealthy and powerful organization. Moreover, the inscrutable Illuminati have planted three spies in the True Cross Order—and one may be hiding among the aspiring exorcists sworn to protect mankind from the demonic threat.

After Mash Burnedead's clash with Magia Lupus, the secret about his powers is now out in the open. The short-lived celebration ends when the Bureau of Magic summons Mash before an audience of Divine Visionaries, who collectively decree Mash should reap the consequences and die. However, an evil shadow organization called Innocent Zero hijacks the inquiry to demand that Mash be kept alive. Mash proves that he is capable of dealing with Innocent Zero, but the Divine Visionaries' verdict remains unchanged. Luckily, Mash finds unexpected allies in Divine Visionary Rayne Ames and Headmaster Wahlberg Baigan, and they successfully defer his execution until Innocent Zero is defeated. Mash is now allowed to live under one condition: he must be selected as the Divine Visionary candidate by the year's end.

Humanity was caught at a precipice a decade ago when the first gates—portals linked with other dimensions that harbor monsters immune to conventional weaponry—emerged around the world. Alongside the appearance of the gates, various humans were transformed into hunters and bestowed superhuman abilities. Responsible for entering the gates and clearing the dungeons within, many hunters chose to form guilds to secure their livelihoods. Sung Jin-Woo is an E-rank hunter dubbed as the weakest hunter of all mankind. While exploring a supposedly safe dungeon, he and his party encounter an unusual tunnel leading to a deeper area. Enticed by the prospect of treasure, the group presses forward, only to be confronted with horrors beyond their imagination. Miraculously, Jin-Woo survives the incident and soon finds that he now has access to an interface visible only to him. This mysterious system promises him the power he has long dreamed of—but everything comes at a price.