Chronos

Chronos is an underground organization that controls one-third of the world's economy. It is commanded by the Council of Elders, who regularly send out its elite assassin squad the Numbers on missions. A select amount of prestigious figures such as politicians and businessmen have connections to the organization. The aim of Chronos is to secure and maintain global peace. This often equates to dismantling organizations and killing people that it considers to be evil or corrupt. However, the society's own tactics and actions are often questioned by those who know of its existence.

Manga
Train Heartnet joined Chronos at age 18 and was infamously known as its best assassin, Black Cat. He was eventually offered the position of being the organization's manager, but declined. Chronos develops significantly in the two years since Train has left and gains control of one-third of the economy. Besides maintaining the world order, Chronos is very cautious about keeping its actions and inner workings private. Since Train knew much about the organization's dealings, the Elders initially want him to return or be killed in order to keep him quiet.

Nonetheless, the attention of Chronos soon turns to a new threat that has the potential to seriously destabilize the world order: the Apostles of the Stars. It is especially important to the Council of Elders because of the direct threat to their power and the fact that the Apostles' leader, Creed Diskenth, was once a member of Chronos. All concern about Train is now directed towards the rogue association. A world conference meeting in San Geles City is disrupted by several members of the Apostles, including Creed. All twenty officials-including seven from Chronos-are assassinated. Thus, the Council of Elders decide to eliminate the Apostles.

Chronos puts out an initial award of three billion dollars for capturing Creed alive. Sephiria Arks and Belze Rochefort, Time Guardians No. I and No. II, visit Train and request his assistance as a sweeper. They leave a copy of the bounty notice with the ex-assassin and don't press for an immediate answer. Meanwhile, plans are already underway to attack Creed. Cerberus, a special attack squad consisting of Jenos Hazard, Beluga J. Heard, and Nizer Bruckheimer, are ordered to kill Creed after twenty sweepers hunting him in Stock Town are found dead. Rinslet Walker is hired to assist them in reconnaissance. Beluga sacrifices his life in order to kill Creed but the deranged man escapes without serious injuries.

Two violent Chronos Numbers, Kranz Maduke and Baldorias S. Fanghini, leave for Stock Town on their own after hearing information that several members of the Apostles are there. They find and aim to assassinate Kyoko Kirisaki but they are deterred by Train, who is in child form at this point. Jenos intervenes shortly afterward and gives them Belze's orders to immediately return to headquarters, as they've caused enough damage to the town and have gone unauthorized in the first place. Lin Shaolee, one of the new Chronos Numbers, attracts the best Sweepers to capture Creed under his disguise as an information broker, Glin. He provides the crew with information of the Apostles' hideout. Since the rogue organization would be preoccupied with fighting the Sweepers, Chronos plans a stealth invasion to catch Creed off guard. Sephiria ends up facing the young man but is overwhelmed by his power. After Train defeats Creed, the Time Guardians briefly thank him and continue to wield incredible power in the world.

Anime
The storyline of Chronos is very similar to that in the manga except for a few major differences. The story begins with Train still holding his position as No. XIII and the agents are called Numbers rather than Time Guardians. Also, Chronos is already a behemoth organization and owns one-third of the global economy while Train's still there. There are several new Chronos Numbers who were never in the manga. Some of the Numbers, particularly Sephiria and Lin, also have major changes in personality. Additionally, Sephiria personally confronts Train and begs him to return. When he refuses, the two engage in a battle and Sephiria aims to kill him. Later, Train catches on to Lin's scheme of using the Sweepers as a decoy for Chronos and the Sweepers' trip to Creed's hideout almost doesn't happen.

The Zero Numbers, a renegade group consisting of stray members of Chronos, sends a swarm of nano-machine beasts to destroy the Chronos Headquarters while the Numbers are busy attacking Creed. As a result, the Council of Elders is assassinated and the organization takes a huge hit in finances and manpower. The surviving Numbers are essentially the only members left in the entire organization. The Numbers assist Train in saving Eve from the Zero Numbers' control and vow to rebuild Chronos.

Ranks
Elder Statesmen/Council of Elders: are three wise elders in charge of Chronos, the highest being Willzark.

Chronos Numbers/Time Guardians: Willzark commands a secret force of the best assassins in the world, sworn to protect Chronos, called the Chronos Numbers, which usually range from No. I to No. XII., (Train) No. XIII is a very special case.

Chronos Erasers: Lower in the hierarchy are the Chronos Erasers, which are assassins in service of Chronos. An example is Creed Diskenth or Cleaver. Other members of Chronos play important roles in the story in the manga, such as Karl Walken.

Chronos Soldier: are normal soldiers in Chronos.

Members
Willzark is the superior to the Chronos Numbers, and the leader of the Elder Statesmen that rule Chronos. He only communicates with the Chronos Numbers through a holographic screen.

The Chronos Numbers
Chronos' top men who assassinate various targets that are in the way of the organization's activities. All the Chronos Number weapons are made of Orichalcum.

Trivia

 * The Chronos Numbers are like a clock because Chronos means time so it will be time numbers and since there are twelve members (Number 13 is a special agent so wouldn't count with the rest of the numbers) like the face of a clock.
 * Every member except Train, Sephiria, Anubis, and Mason wear the same outfit. Though there is a reason, Train is a special agent, Sephiria is the leader, Anubis is a wolf, and Mason is the oldest.
 * Also Belze and Jenos wear slight variations to their outfits. Belze has gold shoulder plates and a coat and Jenos has no tie and his shirt open.
 * Chronos is the only group in both Anime and Manga that does not disband.