Sweepers

In the world of Black Cat, Sweeper is a profession that specializes in capturing criminals for rewards. Sweepers are not unlike bounty hunters, they are licensed by the government and free to move about as they please, however, unlike real-life bounty hunters sweepers are internationally accepted and endorsed by the governments of the world and respected for their contribution to maintaining justice. The pamphlets with information on criminals are spread throughout the world in public places like bars, where Sweepers hang out.

Sweepers vary in their appearance and style of fighting, and many times conflicts erupt among themselves when two or more sweepers go after the same target. The criminals that sweepers have to capture are classified in levels, which range from F to SS, F being the least dangerous and SS the most dangerous. Legendary criminals who may never be captured are considered SS, the most violent and dangerous kind of criminal. An example of the SS is Creed Diskenth, leader and the most powerful member of the Apostles of the Stars.

Chronos

Chronos is the secret organization that rules one third of the world through underground business in various areas. Though despite being a shadow society most characters who spent at least some of their time digging into the underworld know that they exist. Incidentally almost all speaking characters in the series seem to know of Chronos and the Numbers. Most of the Chronos members occupy high positions, such as mayors, politicians, among others. To protect Chronos, there are assassins in the command of the three wise men in charge of Chronos, the highest of them being Willzark. Willzark commands a secret force of the best assassins in the world, sworn to protect Chronos, called the Chrono Numbers, which range from No. I to No. XIII (More information on the Characters Section).

Lower in the hierarchy are the Chronos Erasers, which are assassins in service of Chronos. An example is Creed Diskenth. Other members of Chronos play important roles in the story in the manga, such as Carl Walken, which is the mayor of a town that raised Train and asks him personally to take out a Taoshi who has been causing considerable damage in his city, Gyanza Rujike.

In the anime, the Zero Numbers send a swarm of nano-machine beasts to destroy the Chronos Headquarters while the Numbers were away on Clarken Island, killing the three wisemen. Financial support from practically all sources is cut, but Sephiria, No. I, and the remaining numbers decide to continue in Chronos, although they will have to raise it from its ashes.

 

The Apostles of The Stars

Sometimes simply referred to by the characters in Black Cat as "The Apostles", they are revolutionary group led by Creed Diskenth. Their aim is to "clean the world of filth", that is to say, kill people who cannot achieve the Power of Tao. Naturally, every member of the Apostles of The Stars has a power of Taoshi origin, which are awakened through the Shinkitou, a drink only concocted by Master Taoshis, such as Shiki. Another member of the Apostles, Maro, is also from the forbidden Continent, and together with Shiki, they bear the most traditional Tao power, such as controlling and summoning bugs (Shiki), using ink marks (Shiki) and controlling gravity (Maro).

Other members of the Apostles rely on more "deviant" powers, such as Creed's "Imagine Blade" in the manga, which is a sword that can expand for miles depending on Creed's mental power, even though in the anime Creed's power is just the materialization of a small invisible sword, in replacement for his old Kotetsu, broken by Train. Other Tao powers include Kyoko's "Fire Breath", Charden's "Blood", Durham's "Magic Shot" or Echidna's "Gate".

The Apostles do not just wish to bring about a world revolution, but they seek revenge against Chronos. Creed due to his expulsion after killing Saya, and Shiki and Maro due to the war that happened between the Taoshi and Chronos long ago, which decimated the Taoshi from the Secret Continent. Although Tao has been the primary source of the Apostles' power, Creed also relies on Doctor's investigations on Nanomachines to grant him eternal power and elevate him to a god.

The Taoshi War

Many decades in the past, there was a war between the Taoshi and Chronos. Chronos eventually won, even though not all Taoshi were killed. In the current Chronos, the only Number that witnessed this War was Mason, which himself became a Taoshi, granted with the Sacred Technique. However, he had kept this from everybody in Chronos, planning the Eden project for a long time (More information below).

The survivors among the Taoshi that make an appearance in Black Cat are no more no less than Shiki and Maro, which upon meeting Creed grant him the power of Tao in exchange for an alliance which objective was to destroy Chronos and bring about a revolution to this planet, which would choose the Taoshi among the people, and rid everyone else.

 

Nanomachines, Eve, Dr. Tearju, and Dr. Kanzaki

The nanomachine investigation by Dr. Tearju Lunatique allowed her to achieve the knowledge that might allow her to create a prototype of a human that could transform and eventually become the ultimate weapon. In the manga, Creed Diskenth financed the research of Dr. Tearju, hired by Torneo Ludman, to create Eve, which would be the perfect weapon for him to use, while in exchange Torneo promised to have Dr. Tearju research nanomachines in the areas that were of Creed's interest, such as the legendary immortality nanomachines.

Eventually, Dr. Tearju realized she couldn't do that and quit, for the world's safety, but due to blackmail from her former assistant, one of the Apostles, Doctor, or Dr. Kanzaki, she passed him the nanomachine research documents, which allowed Doctor to perfect them in order to make Creed a god. Worth noting is that in the Anime, Dr. Tearju didn't pass the documents on to Doctor, which stole them instead. In the anime, he also used them to produce the Eden machine that would work when combined with Eve.

The Zero Numbers and Eden

The Zero Numbers are the Chrono Numbers gathered by Mason to aid him in the Eden project, which he planned since Eve was created by Dr. Tearju. The Eden project consisted of bringing "World Peace", which would actually consist of turning every single person on the Earth into creatures without mind of their own, only capable of obeying the Zero Numbers. The Zero numbers were also implanted with nanomachines that allowed them to be immortal within Eden's energy field, created by Doctor.

For Eden to work, however, it was needed that Eve entered it, in order to combine with the program inside Eden, Adam, to put into motion the giant creature, which was Eden combined with Eve. Mason had gathered people from Chronos, from the Apostles of The Stars, in order to aid him when the time to retrieve Eve came.

That is because Eve needed to be raised well in order to be "perfected", and since the day she met Sven and considered him the ideal "father", Mason decided it would be of best interest to the Zero Numbers that Sven and Train raised Eve, and they would retrieve her, like happened in the story.