Devil Survivor

Akemi Nakajima is a student in the "gifted class" in his high school. After being bullied and beaten by another student who a female student invoked, Nakajima uses his advanced computer skills to create the "Demon Summoning Program."
He summons demons to attack the two, but he gets carried away and ultimately kills them. Now sick with the power of the demon realm Makai in his hands, he summons the demon lord Loki. Realizing summoning such a powerful demon was a mistake, Nakajima sets out to reverse the problem he has created by any means.

The setting of Devil Survivor 2 spans the whole country of Japan. It tells the story of Japanese high-school students who receive emails from a website foretelling their friend's deaths. Mysterious creatures invade the country, and the students enter a pact, enabling them to summon demons from their cell phones with a special Devil Summoning App.

While Japan in desperate situation, 13 "devil survivors" cut deals with devils to obtain abilities to fight against unknown invaders with only 7 days left until a world catastrophe, you need to make crucial decision to survive...