Shin Megami Tensei: Tokyo Requiem

The story begins in December 24, 201X in Tokyo. The protagonist is meeting his girlfriend for a date. Suddenly, he receives a mail on his mobile phone. Attached is a file called the D.I.O. System, a demon summoning program.

At that point, a flash of light passes before the pair's eyes. Tokyo is destroyed in a nuclear explosion. Tokyo's Information Systems collapse. Out of the mountain of debris, survivors encounter a countless number of strange beings.