Giten Megami Tensei: Tokyo Mokushiroku

The game is set in an alternate reality, in which Tokyo is invaded by hordes of demons. You play the role of a young man who lives in an underground shelter and is training to become a demon hunter with help of special programs. One day, during a training, one of the programs goes berserk, and as a result you are thrown into the world where you must fight for your life against vicious demons.