The four main human characters in the game are given no default name. Instead, the player is allowed to name them and assign their statistics. For the PlayStation remake of the game, they were given names in the official strategy guide "Steven Report 1". The artbook, Kazuma Kaneko Complete Illustration Works also gives English names to each (except for Heroine).
Hero
The player character and protagonist of the game, although never shown to speak. The Hero is given a Demon Summoning program by Steven at the beginning of the game, and is able to use it because of his innate talent. He is caught up in events when he is falsely accused of murder and thrown into prison, where he meets Law Hero. Later he meets Chaos Hero and joins forces with Heroine to stop the launch of the nuclear missiles that would destroy Japan. He fails, but survives when the Heroine teleports him to the safety of Makai.
It is his destiny to create the new world as the new Adam, but what kind of world he creates depends on his experiences in the aftermath of the Great Destruction. If he chooses the Law alignment, he creates the Thousand Year Kingdom of God with the angels. If he chooses the Chaos alignment, he creates a world of demonic anarchy with Lucifer. If he chooses the Neutral alignment, he destroys both the angels and the demons and seeks to create a world of true freedom, built by the hands of man.
A statue of him can be found in the Colosseum in Shin Megami Tensei II, naming him as the "first champion".
In "Steven Report 1", he is given the name Kazuya and in the "Kazuma Kaneko Complete Illustration Works" he is identified as Futsuo.
Heroine
The leader of the underground Resistance movement against the machinations of Gotou, the Heroine is a strong woman who is saved by the Hero during a prophetic dream at the beginning of the game. She is also shown to have incredible spiritual powers, and saves the Hero, Law Hero and Chaos Hero by teleporting them to Makai moments before the Great Destruction. She is spiritually linked to the Hero as his destined partner in creating the new world; the Eve to his Adam.
She is killed during the Great Destruction, but is reincarnated as a young girl who is rumoured to be the Messiah, forgetting everything about her previous life except for her link to the Hero. She is captured in Shibuya and has her mind invaded by a demon who begins devouring her sanity from the inside out. As she is spiritually connected to the Hero, he feels her incredible pain whenever the moon is full and loses some of his health. With the help of the PsychoDiver, the Hero is able to enter the Heroine's mind and eradicate the demon within, freeing her from its control. Regaining the physical form of her past life, she stays by the Hero's side until the end of the game, no matter which alignment path is chosen.
In "Steven Report 1", she is given the name Yuka.
Law Hero
A young man who is first encountered by the Hero in jail, having been captured while searching for his girlfriend, who happens to be the Hero's next door neighbor. He is shown to be kind and compassionate, but also extremely determined in achieving his goals.
After the Great Destruction, he naturally gravitates towards the message of peace broadcast by the Messian religion and eventually becomes enthralled by it. He is killed when his soul is stolen from his body by a demon called Black Baron. His soul is liberated by the Hero, and a messenger of God-- believing him to be worthy-- guides his soul to heaven. He is later resurrected as the Messiah, whose task is to establish the Thousand Year Kingdom, a supposed paradise on Earth ruled by God. Now completely dedicated to God, he follows the orders of the angels without question, believing his cause to be righteous and infallible. In the Neutral and Chaos alignment paths he is killed by the Hero, while in the Law alignment path he is killed by Chaos Hero.
In "Steven Report 1", he is given the name Yuji and in the "Kazuma Kaneko Complete Illustration Works" he is identified as Yoshio.
Chaos Hero
A violent young man who is first seen being beaten up by a gang of thugs led by a man named Ozawa. He joins the Hero to get revenge against Ozawa for humiliating him. In contrast to Law Hero he is quite cruel and unforgiving, believing that people should stand with their own power and refusing to offer aid to the needy. However, despite his tough talk he is shown to be emotionally weak, and is always relying on others for companionship and emotional strength.
After the Great Destruction, he attempts to kill Ozawa (who has become the ruler of the Shinjuku district) but fails when Ozawa summons a powerful demon as his bodyguard. He comes to the conclusion that true strength comes from demonic power and fuses himself with a demon at the Jakyou, gaining incredible strength. He easily kills Ozawa and leaves the Hero, proclaiming that he has no further use for him. He later takes on a girl called Rie (Chaos Heroine) as his companion and joins forces with the demons to bring about an era of anarchy. In the Law and Neutral alignment paths he is killed by the Hero. In the Chaos alignment path, he is consumed by the raw power of the Devil Ring he greedily snatches from the Hero, dying in the process.
In "Steven Report 1", he is given the name Takeshi and in the "Kazuma Kaneko Complete Illustration Works" he is identified as Waruo.
Yuriko
A beautiful woman who pledges to be the Hero's eternal partner, promising to always stay by his side. Her true identity is Lilith, a manipulative, shapeshifting demon who desperately wishes to be Hero's Eve in creating the new world. To this end, she attempts to get rid of everyone close to the Hero so that he will only be able to rely on her, kidnapping and imprisoning the Heroine (the true Eve).
After the Great Destruction, she becomes the companion of Chaos Hero as Rie, the Chaos Heroine. This is so that she can get close to the Hero, her true objective. In all the alignment paths she is killed by the Hero, but in the Chaos path she expresses more regret for her actions and asks the Hero for forgiveness before she dies.
STEVEN
A disabled computer programmer in a wheelchair who wrote the Demon Summoning Program. This program allows someone to converse with demons and store them as digital data on a memory chip, though only those possessing natural talent would be able to use it properly. It also possesses an Auto-Mapping function. Knowing of the imminent threat of the demonic invasion, STEVEN sent his program to as many people as possible through the Internet with the hope that some would be able to use it to either avert the coming crisis or survive in the world it created.
STEVEN was also the main architect of the Terminal System project, whose goal was to develop instantaneous travel between computer terminals. During one of these experiments, a terminal was accidentally connected to Makai, causing a demon to appear and inflict the crippling wounds that have caused Steven's current condition. His bitterness at this was the motivation for the creation of the Demon Summoning Program, which would capture and bind those demons as allies.
He survives the Great Destruction and can be found in Ginza, where he upgrades the capabilities of the Demon Summoning Program to allow the Hero to store more demons and summon more demons at once. He survives in all alignment paths and reappears in Shin Megami Tensei II, though his appearance is unusual considering Shin Megami Tensei II takes place decades after the first game.
He is based on the real-life theoretical physicist Stephen Hawking (who is also a wheelchair user).
Goto
A charismatic military general who acts as the catalyst for the Great Destruction. After learning that Steven's Terminal System had created a portal to Makai, he sought to use these demons as a military force to prevent the establishment of the Thousand Year Kingdom of God, a conspiracy that had started long before the events of Shin Megami Tensei.
As an avid follower of the Gaian religion, he believed that Mother Gaia had been forgotten and neglected, leading to the current state of the world. He also believed that the demons were ancient gods that had been awakened to heal the broken planet and prevent its destruction. Learning of an American plot to destroy Japan with nuclear missiles (which was actually due to the manipulations of Thor), he instituted martial law in Tokyo and began building up an army of demons to fight the incoming threat. Knowing only the name of the leader of the Resistance opposing him, he ordered the capture of any girl with the same name as the Heroine.
He is killed by the Hero in the Law or Neutral alignment paths, and killed by the Great Destruction in the Chaos path.
Ozawa
A cocky gang leader that is first seen beating up Chaos Hero in the Shinjuku Mall. It is revealed that he has the same demon summoning talents as the Hero, and joins forces with Goto with the intention of one day usurping the general's position and seizing control for himself.
He survives the Great Destruction and becomes the ruler of the Shinjuku district, striking a deal with the demons that allows humans to live there but under his command. Anyone who disobeys him is captured by his secret police and brainwashed by the PsychoDiver, another one of his subordinates.
When the Hero's party first meets him after the Great Destruction, he doesn't recognise them and summons a powerful demon to act as his bodyguard. This prompts Chaos Hero to fuse himself with a demon at the Jakyou to gain the power necessary to successfully kill Ozawa.
Ambassador Thorman
The American ambassador to Japan. When he learns that Goto has discovered a way of summoning demons from Makai and intends to stage a coup d'état, he calls upon the American military to provide resistance against the threat. He later asks the Hero for his assistance in defeating Goto to prevent the demons from overrunning the Earth.
His real identity is Thor, an agent of God dedicated to the establishment of the Thousand Year Kingdom. Whether or not the Hero successfully kills Goto for him, he obliterates Japan with his "Hammer of Thor" (a barrage of ICBMs) to further the cause of the Thousand Year Kingdom. He is killed by the Hero in the Neutral and Chaos alignment paths, and survives in the Law alignment path.
Louis Cyphre
A young man who can be found after the Great Destruction observing the Hero's actions. He hints at a much greater knowledge of what is happening, and seems to befriend many demons quite easily. He is in fact a human pseudonym of Lucifer who appears in each one of the three "Shin Megami Tensei" games.
At the end of the Chaos alignment path he appears in his true form to offer his congratulations to the Hero for defeating the God of Law and resurrecting the olden gods, but warns that the "true enemy" (referring to YHWH in Shin Megami Tensei II) still exists.
Old Man
An old man who the hero first encounters in Inoshigire Park who senses the danger that is to come to Tokyo. He survives the Great Destruction and can reveal the hero's current alignment by reminding him about what is right or wrong. His true identity is Taishang Laozhun.
