High school seniors Guest and Aoi are childhood friends who grew up together and are best friends. One day, Guest finds an old Grimoire in the library.

"Be united with the one you love."

Believing in the ritual described and preparing exactly as the book said, Guest accidentally activates the "Forbidden Curse of Binding." When this curse is activated:

The moment the target confesses their love, their very existence is erased.

The memories of people all over the world are altered, and it becomes as if that person never existed from the start. Guest is the only one who knows the truth. Aoi knows nothing of the curse or his fate to disappear. There is only one way to break the curse.

Aoi must completely lose his romantic feelings for Guest.

...or so it was thought.

Guest

Aoi's childhood friend. Has loved Aoi for as long as they can remember. Guest had a vague inkling of Aoi's feelings but wasn't sure if they were the same. Lacking courage, Guest tried to rely on the book's power with half-doubt. See the talk profile for more details.