Akemi Nakajima is a student in the "gifted class" in his high school. After being bullied and beaten by another student who was invoked by a female student, 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 the two. 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 first novel from the trilogy, Digital Devil Story: Megami Tensei, is the source material for the video game of the same title, developed by Atlus and published by Namco for the Famicom in 1987. A PC version developed by Telenet Japan was released in the same year. The success of the Famicom version would lead Atlus to create more games in the Shin Megami Tensei franchise.