|“||Understand that there is no joy in living. Cry, that there is no answer! Where there is darkness, there are shadows. I, myself, am all of you humans!||„|
Nyarlathotep is the personification of all of humanity's evil taken form, able to take any form he wanted. He is the evil counterpart of Philemon, who represents the good of all humanity. At one point, the two of them made a bet about the fate of humanity: Philemon believed that humanity would reach enlightenment and trascended themselves, but Nyarlathotep believed that humanity would destroy themselves. However, Philemon is only limited to guiding the humanity to find their goodness, while Nyarlathotep actively intervenes humanity in order to ensure that he is the winner of the bet.
Persona: Be Your True Mind
Nyarlathotep makes his presence known at first by becoming the Persona of Takahisa Kandori, the CEO of SEBEC company, manipulating him to fulfill his delusions of Godhood and utilizes the DVA System using the subconscious of Maki Sonomura in order to start the first step of the destruction of reality through the destruction of Mikage-cho with the alternate reality provided by DVA System. Kandori is defeated and Maki is restored to normal. However, no one knew that it was Nyarlathotep pulling the strings from behind.
The first English localization of the game changed his name into Massacre. It is possible to obtain Nyarlathotep himself as a Persona in this game by fusing a Tower Arcana Persona using the item obtained from defeating Kandori the last time. However, not only he has the worst affinity to every party members except Kandori's brother Reiji, his form is considered massively weaker than the form he used as Kandori's Persona.
Persona 2: Innocent Sin
Nyarlathotep takes the next step of his game by granting the people in Sumaru City the power to make rumors turn into reality, throwing the whole town in chaos. In addition, he manipulated Jun Kurosu into becoming Joker with the basis of making his friends pay for a sin they chose to forget, acting as his Persona. His friends; Tatsuya Suou, Eikichi Mishina, Lisa Silverman and Maya Amano; snapped him out of it and Nyarlathotep took another guise, this being Jun's idolized father Akinari Kashihara.
Nyarlathotep seemingly took form of Akinari's Persona. However, around this time, one nasty rumor about Adolf Hitler surviving and is hiding, waiting the time to restart his reign, comes into fruition and the Nazi came back, assaulting Sumaru City. When Tatsuya and his friends confronted Hitler, Hitler claimed that he's using Nyarlathotep's power. It turns out, however, that Hitler was in fact yet another guise of Nyarlathotep.
Nyarlathotep reveals his bet with Philemon to the team and attacked them afterwards. While defeated, Nyarlathotep had the last laugh, previously he manipulated a deranged teacher Maya Okamura to be his follower, based on his appearance as Akinari. As a result, Okamura appears and gored Maya Amano with the Spear of Longinus, with the rumors surrounding the spear that any wounds caused by it would not heal. As Maya died, another plan of Nyarlathotep came to fruition: All the chaos he's causing is eventually part of the prophecy written in the book In Lak'ech, the creation of the book itself influenced by him. The prophecy spoke of the destruction of all realities. Maya's death triggered the part where the destruction commences and Tatsuya could only witness as all realities crumble, leaving only Sumaru City and Nyarlathotep laughing triumphantly over his victory.
His victory, however, was undone when Philemon gave the remaining heroes a way to undo his victory: By sacrificing their memories of their meeting, so all these would not happen. As the heroes did so, the realities were restored. However...
Persona 2: Eternal Punishment
Despite his victory undone, Nyarlathotep stayed calm, he has prepared another way to restart his plan and once again come out victorious. He took advantage of the fact that Tatsuya turns out to be extremely insecure, and in the last minute, refuses to sacrifice his memory. As a result, Tatsuya of the old world took over the Tatsuya of the new world. Around this time, a new phenomenon is appearing in Sumaru City in form of the Joker Curse about a paper-bagged serial killer called Joker. This too, is a plan of Nyarlathotep, to recreate similar events to lead to the end of the world.
His other plan involves restoring the memories of the old world to the new world's Eikichi, Lisa and Jun, that they were Persona users. By doing so, it would once again trigger the destruction of the world. He succeeded in capturing them, but were eventually confronted by a new group of heroes, aside of Tatsuya and this world's Maya Amano, there's also Tatsuya's brother Katsuya Suou, Maya's friend Ulala Serizawa and information-broker Kaoru Saga/Baofu. After confronting and torturing their psyche, Nyarlathotep once again launched his assault. However, at this time, Tatsuya has found enough resolve to not run away from his sins of the previous world. Philemon eventually confronted Nyarlathotep and declares victory, that the humans would not lead themselves to their destruction. Nyarlathotep accepts defeat, but warns the heroes that he would never truly vanish, as long as humanity exists and continue to do evil as he is a part of humanity that could never be removed.
Persona 4: Arena
In this game nyarlathotep is implied to be the malvevolent entity that is the antagonist of the game.