Kabane

Origin
It is a fact that a monster had suddenly appeared capable of infecting humans with its bite but other than that at present the Kabane's origins are entirely unknown. It is simply stated that their appearance twenty years prior to the story is what caused people to construct stations and the railways linking them. It seems most of the general populace considers them a curse, or at least something supernatural. However, Ikoma and Takumi have hypothesized that it seems more akin to a virus, something Ikoma had the morbid pleasure of discovering firsthand after being bitten and infected. That being said, it does seem that there are more people attempting to look into the Kabane, as both state that Kongoukaku is the prime location for Kabane related study and research. It appears that this phenomenon has occurred across the globe.

Physiology
Kabane maintain their general human shapes upon transformation, though that seems to be the extent of what remains. Their skin darkens to a cold gray, their veins seem to glow molten yellow, and their eyes blacken to the point where only their pupils gain a menacing red glow. It is unknown if the change in coloration of the blood vessels is simply a mutation, or if they actually carry molten iron in their veins, as their heart radiates a bright molten color and is surrounded by a hardened iron cage that is resistant to conventional steam weapons.

Their skin seems to be extremely tough. When their heart cage is pierced by bullet or sword they produce sharp sparks whenever pierced, typically in blue coloration. They lack any sort of fear of death, as they will not shy from flames, gunfire, and even Hayajiro. They have maintained some form of human intelligence, however, as they have shown to be capable of basic ambushing, utilizing simple weapons and even hijacking the Fusōjō in order to breach Aragane's west gate. Whether this is a remnant of their human selves or just instinct is undetermined.

The exact strength of a Kabane is hard to measure; with their bites, they are easily capable of tearing human flesh by the chunk, single-handedly swinging and hoisting up male adults, holding on to speeding Hayajiro without a problem, damaging and sometimes tearing away steel doors, and even damaging extremely thick steel plating with mere headbutts - however, they have been seen to be physically resisted and pushed aside by normal humans, and the force from bullets seems to be able to knock them back. A fair assessment could be that they lack the fine motor skills to gauge their own force and restraint at different times, as Ikoma has noted that he doesn't know his own strength soon after becoming a Kabaneri.

They are also extremely quick on their feet, and being able to jump enormous distances through the air.

Types of Kabane
Kabane are classified according to their appearance and abilities. The following is a list of various known Kabane in the series.

Trivia

 * It appears Kabane can be killed by beheading them, as Mumei showed when she beheaded one with her heels.
 * It appears that Kabane do feel sympathy towards their own, when Mumei beheaded a Kabane to distract others it was shown that the Kabane clearly felt angry towards Mumei. It is not clear why they feel anger from this but it could be same reason why bees attack en masses on an intruder, meaning hive mind like operation that becomes hostile if one of it's own is attacked/killed.
 * It appears that since blood contains iron the Kabane are biting people to reinforce their heart cages, which is shown to be a mass of molten iron like substance. This is further evident because the  Kabanes  do not eat the bodies, they only bite their victims in the neck, if possible, to get as much of blood as possible. This shown in the third episode when Ikoma tells about his sister's death, he fled and once he returned the body was not eaten, only bitten in the neck and drained of blood.
 * Kabane is written in Japanese in katakana, a written style mostly used to denote a loanword. However, the word kabane is an actual Japanese word, usually written with the kanji 屍, meaning dead corpse. The more widespread reading of this kanji is shikabane. While the first syllable shi- in shikabane sounds like the word shi 死, meaning death, one would think that the authors deliberately chose the less common pronunciation of the kanji 屍 for Kabane to specifically design undead corpses.