Joker

is a mysterious man that appears to have knowledge of Shinra's past.

Appearance
He is a tall man who appears to be in his early adult years. The man has long and stringly black-coloured hair, that falls below his neck. He wears a black top-hat and a black bandanna across his face, with a pattern on it, that covers his left eye, an old-fashioned shirt with a black waistcoat, white trousers and shoes. His iris appears to be spiral-shaped. The man is commonly seen smoking a cigarette and appears to always carry a sadistic expression.

Personality
The man appears to be quite sadistic, as he enjoys hurting people and toying with their emotions. He's also willing to offer information to people, in exchange for entertainment.

Abilities
Being a Second Generation, the man has adapted to the phenomenon and was granted the ability to control flames, however, he cannot produce flames from his own body. He uses the fire of his cigarette to create various card-themed signs, like a suit of cards or card-shaped projectiles. The man is also shown to use some sort of sand-like substance in a bottle, which can create instantaneous explosions or cause things to burst into flames. He is skilled in hand-to-hand combat, as he was effortlessly capable of dodging all of Shinra's fiery kicks with ease, as well as keeping the boy on his toes the entire time.

Introduction arc
Unbeknownst to the 8th Special Fire Brigade, who were in the middle of a mission to kill Mikako's father, who was a Flame Human at the time, the man gets involved with the caving in of the apartment, using an unknown, powdered medicine-like substance he obtained from a man in a science lab beforehand. He later confronts Shinra inside the Haishima Heavy Industries, during the Fire Officer Newcomer Tournament, and taunts him about his past, claiming that he knows the truth behind it. He then threatens to kill the unconscious people around him, which causes him to engage in a battle against Shinra, where he dodges all of the boy's kicks with relatively ease. The man then picks up a bottle from inside his pocket and throws it to the ground, which causes an explosion. Using it as a diversion, he heads in for an attack, knocking Shinra back using hand-to-hand combat. Then, the man throws card-like projectiles at the boy, injuring him. He steps up, wondering whether he should kill Shinra or not, and notices his expression, which amuses him enough to give Shinra a reward in the form of information that his brother, Sho, is still alive.