Through the tradition of the Megami Tensei series, he is a silent protagonist, where his personality is based upon players' actions and decisions, a tradition which later Shin Megami Tensei protagonists would follow.
The protagonist and his friend were playing the video game 'Devil Busters' in the Keihin (京浜) Shelter No. 3. When they beat the first boss, they unseal Pazuzu inside the game and are given the Demon Summoning Program along with a warning of a coming menace. Zombies then begin to raid the shelter and the two friends must save the remains of humanity.
Whatever the player chooses, the protagonist can reach one of the possible endings of the game.
- In the manual for the game's original release, he is given the name "Hideto". This is a reference to music duo Hide and Rosanna, as well as a pun on their name.