Infernal

The victims are people who have unexpectedly caught fire, resulting in them turning into Flame Humans. The process is quite painful and is the most feared cause of death. Due to them rampaging and commonly losing all rational, Special Fire Brigades have been tasked with extinguishing and purifying their souls. Flame Humans are known to vary greatly individually, with some being more adept in battle than others, and even having self-awareness.

Overview
The Flame Humans have no reason and rampage until their lives flicker out. They are capable of launching fireballs and get a notable boost in power and speed, and have more than one appearance, though they all form around a black figure enveloped in fire. Flame Humans have also shown the ability to absorb surrounding flames and use them either for offense or defense. The only known way to kill a Flame Human is to impale their core, located in their chest, which is a painless method of returning them to the raging flames. Humans also tend to pray for the souls of the defeated Flame Humans, as a way of purification. It is known that if a person transforms into a Flame Human while having a strong attachment to life or some great willpower, they will keep their self-awareness; though the level of consciousness differs with each individual.

Victims

 * Mikako's mother fell victim to the phenomena in year 196.
 * A man boarding a train, completely transformed into a Flame Human and set fire to the train carriage. He was later killed by Akitaru Ōbi.
 * Saeko fully transformed into a Flame Human, resulting in the woman damaging her husband's workplace and killing an employee. She was killed by Shinra Kusakabe.
 * Mikako's father partially transformed into a Flame Human while remaining conscious through the ordeal. He was soon killed by Arthur Boyle without any resistance.
 * Setsuo Miyamoto fully transformed into a sentient Flame Human, murdering multiple people before being captured and experiment on by the 5th Special Fire Brigade.

Trivia

 * The chant that the Special Fire Brigades preach before killing a Flame Human ("Ashes to ashes, dust to dust") is a phrase taken from the funeral service in the Book of Common Prayer.