Ghoul

Ghouls are a carnivorous and cannibalistic humanoid species that are only able to feed on the flesh of humans and other ghouls. They are as close to humans as possible: they normally display the same attributes; the same physical appearance and intelligence as a human with the main exception being their inner biology, mentality, and diet.

Diet
A ghoul can only feed on humans and other ghouls. They are unable to digest any other type of food due to a particular enzyme their bodies produce. The structure of their tongues is also different from humans', making other foods taste disgusting and uncomfortable. If ghouls attempt to eat normal food, they will be struck by a powerful urge to vomit. (Some hybrid Ghouls can eat normal food.) While ghouls cannot eat normal food, they are, however, able to drink coffee, as well as regular water.

Ghouls do not need to eat regularly like humans do. They can survive for one or two months on just one body. However, some ghouls eat merely for pleasure.

When a ghoul enters an extreme state of hunger, they will suffer very painful headaches and their mental ability will be impaired, causing them to become driven by instinct alone.

Abilities
Ghouls have a high physical capability and are four to seven times stronger than the average human: they can penetrate a humans body with their bare hands. They are also capable of jumping to heights not achievable by a regular human. Their bodies are extremely resistant to injury. For example, if a ghoul gets stabbed by a knife, the knife would break instead, suffering a small scratch that heals almost instantly.

Ghoul senses are much keener than those of humans. They can smell people or meat from afar.

Lifestyle
Ghouls had two choices of lifestyle: living as hermits; isolated and avoiding society's eyes, or attempt to assimilate into human society. However, after the unification, co-existence was promoted. Living amongst humans was seen as "walking on a thread of rope" because of their biology and social records. Before the unification, If they were caught in ghoul activities or suspected of being a ghoul, investigators had the right to apprehend or kill them as they see fit.

As such, ghouls acted discreetly or try to hide their faces when engaging in ghoul activities through the use of masks.

Ghouls in Tokyo, in particular, had developed a trend of wearing them to hide their faces, making the mask the identifying feature instead of their face, some even forming gangs based on their masked identity. Since the ghouls are only identifiable by their masks, they are safe so long as their face is not exposed.

Some ghouls prefer to live as hermits instead. Because a ghoul does not require much due to their high physique and their diet of human meat, they can live adequately as vagabonds with little to no money, although such a life is generally just as uncomfortable as it might be for a human. Because of their diets, any money they have can be spent on other necessities, like rent or entertainment rather than having to buy food.

Ghouls can pretend to eat food in order to fool other people into believing they are human. However, they must make themselves throw up soon afterward, or they will become sick. Because they can only consume human flesh, they are very territorial when it comes to, "hunting grounds" on which it is appropriate to hunt humans without notice.

Variants
- A one red-eyed ghoul is a rare human-ghoul hybrid, either created artificially or naturally born between inter-species relationships.

- A Quinx is a variation of artificial one-eyed ghoul created by the CCG with restrained kakuhou through the use of quinque steel.

- An Oggai is another variation of artificially created one-eyed ghoul, also created by the CCG through the use of Rize Kamishiro's kakuhou. However, after the destruction of all 100 Oggai and the death of Rize Kamishiro, creating any more Kamishiro Oggai would be near impossible.

- A half-human is a human-ghoul hybrid born without ghoul abilities.

Weaknesses
Human food will make them struck by a powerful urge to vomit.

(More W.I.P)