Ages ago, an evil Demon Beast known as Eyrith was sealed into a stone slate by Makai Priests using nine other Horrors as foundation stones. In the present day, the slate was uncovered and while being exposed at a museum, it is unsealed by a mysterious figure, and one of the Horrors possesses the body of the security guard Sekiya who has been watching over the museum that night. Meanwhile, an unknown woman wakes up from a grave at an unknown location. At the Saezima estate, Raiga Saezima is informed about Eyrith's advent and that a magic tool is being sent from the Senate to assist him. Raiga then starts his investigation with Zaruba when the mysterious woman meets Sekiya and starts trailing him. When night falls, Sekiya confronts the woman and just as he is about to attack her, Raiga appears to confront him, revealing himself as the current Garo. Zaruba then identifies Sekiya as the Horror Azdab who attempts to flee, but is slayed by Garo before he can go. Instead of being sealed into the Garoken, Azdab is transformed into a small stone and the woman introduces herself as Mayuri, the person mentioned in the letter from the Senate. When Raiga asks her about the magic tool he was entrusted to, Mayuri seals the stone into her own body, revealing that the magic tool in question is actually herself.
