Rei Ametani's life is nothing but mundane; he's just waiting for death to take him. Despite being a gifted trumpeter in his youth, he struggles to stay awake during classes. However, everything changes when he finds a note in his shoe locker claiming to be a declaration of love. Intrigued, he agrees to meet the sender, but it's not a love confession. Instead, Sora Kamizono approaches him with a request to help destroy the world.
Kamizono, one of the Seven Angels mentioned in the Book of Revelation, is on a mission from God to bring about the end of the Earth using her trumpet-playing skills. The only problem is she's not very good and needs Ametani's help. Despite his eagerness for death, he agrees to mentor Kamizono for the next seven days. As the past and present start to mingle, both Ametani and Kamizono start to doubt their mission.
