Kazuya and two friends take handheld COMPs from his cousin Naoya, then start receiving Laplace Mail: short clips showing how the people around them are about to die. The devices turn out to run a demon summoning program, demons break loose across Tokyo, and the government seals the city off with the three of them inside. This manga follows Atlus' Devil Survivor through that lockdown, the trio trying to break the deaths the mail keeps announcing.