In Ultraman season 3, Mephisto serves below Edo and convinces the humans to turn against the Ultramen through his elaborate plan.
In the third season of Ultraman, Shinjiro struggles to get hold of his enhanced powers. At the same time, he also dreams of Zetton, the monster his father fought years ago.
While Shinjiro is busy figuring out what is wrong with him, Mephisto brings more trouble to his door. He puts his minions, Zaraby, Zaraby’s brother, and Valkyura, to work and attempts to show humans the kind of threat these Ultramen are.
Zaraby’s brother takes on Ultramen’s form and goes berserk in the cities while Shinjiro is away, framing Shinjiro for the destruction caused.
Mephisto’s goal
The motive of Mephisto and Edo is to take out all four Ultramen who can use the Specium Beam, as in the Giant of Light. In the finale, Edo reveals that the Star Cluster Council planned to invite humans in, but the unshakable faith of humans in Ultramen stopped them from making this move.
The Star Cluster Council sees Ultraman as someone powerful who has a one-sided sense of justice. They won’t allow such a menace to roam the world. Humans, on the other hand, see Ultramen as their protectors.
To bring humans on their side, Mephisto and Edo need to prove that Ultramen are a threat. This way, their killing of Ultramen can be justified.
Mephisto’s job is to convince the humans that they will suffer because of the Ultramen’s aggression during the battles. Mephisto successfully creates this narrative with the help of Zaraby’s brother, who can take Ultramen’s form and destroy cities.
Meanwhile, Shinjiro walks right into Mephisto’s trap when Mephisto kills his father. Shinjiro releases the aggression Mephisto wants him to. This new brutal form of Ultramen convinces the people that Ultramen are just as dangerous as the aliens they fight.
Once the word against Ultramen is spread, Mephisto goes live on television and social media to push the narrative that Ultramen should be eliminated. Hence, the anti-Ultramen sentiment grows.
Mephisto also sends his minions inside SSSP. Zaraby fights Shinjiro and lures him into killing him brutally. Kotaro witnesses Shinjiro’s actions, and now Shinjiro’s friends look at him as a threat as well.
Mephisto’s death
Shinjiro escapes the custody of the SSSP to prove his innocence. He returns with Kotaro and Jack once he does. When Mephisto’s minions fail to bring Ultraman down, Mephisto decides to make moves on his own.
Mephisto kidnaps Rena to bring Shinjiro out. He then lures Shinjiro into using the Giant of Light and going berserk. Shinjiro manages to kill Mephisto this way, but people become more convinced that Ultramen are a menace.
Mephisto, on the other hand, before dying, uses Shinjiro’s Giant of Light to power Edo’s spaceship, which will summon Zetton.