Setsuo Miyamoto

is a former firefighter, who was turned into a Flame Human.

Appearance
As a human, Setsuo was a bald middle-aged man with a stubble and a very devious appearance. He was last seen wearing a prison uniform, given that he was a criminal. When the man fell under the Human Body Ignition Phenomenon, his skin turned dark and parts of his face, above his cheeks, disappeared, leaving a vertical lining above his mouth serving as his eyesight. Setsuo has a large mouth and muscular physique, and wears white trousers with black shoes. Through the transformation, the handcuffs he was wearing turned into flames, in the shape of a "∞".

Personality
As a human, Setsuo appeared to be a troubled and psychologically disturbed man, and was dubbed insane after killing four innocent people. He doesn't have concern for the well-being of others, as he recklessly directed his flames and burned two people, and displays ill intent. As a Flame Human, Setsuo becomes driven with killing everyone in sight, bringing them painful death in the process.

Abilities
As a Flame Human, Setsuo has shown the proficiency to speak and have self-awareness. Due to Setsuo being a Flame Human, he has the ability to manipulate and produce flames from his own body.

Background
During his time as a firefighter, Setsuo managed to kill four innocent people, became mentally disturbed and was sentenced a life in prison. In court, he acted like he lost his insanity.

Plot
On the final day of his trial, Setsuo was deemed not guilty for the actions he had done in the past, by reasons of insanity. As he leaves the court, Setsuo's hand starts to envelop in flames, a sign that Setsuo was slowly becoming a Flame Human. In the midst of his transformation, Setsuo kills two bystanders, who were laughing at his misfortune.