Far from mainland Japan, there’s a small island where oni and humans co-exist which has two gates connected to the afterlife. The entrance is located within the human’s territory and exit in the oni’s lands. The two groups struck a deal in the past whereby the oni protect the humans by defeating the “apparitions” – which are supposedly evil souls that escape from the afterlife via the oni’s gate. The human’s part of the deal is that their shrine maiden must maintain the power of the two gates and make magatama that the oni use to help them fight the “apparitions”. However, due to past tragedies, the humans and oni despise each other and try to stay as separate as possible

• The protagonist, Carlisle Varariel, has recently been told that he will be taking over the role of the shrine protector from his grandmother. Information then comes in that something unusual has been happening to the gates and so he is sent to investigate the oni’s gate.
• Through his involvement with the oni, he gets to know the secret of the island and the fate of the oni.