Arbiters

The Four Rules of Arbiters
1. Arbiters cannot quit making judgements, for that is the reason why they exist.

2. Arbiters cannot experience death, for that would bring them too close to being human.

3. Arbiters cannot feel emotion, for they are dummies.

The fourth rule was added in by Oculus after seeing Decim judge Chiyuki.

4. Arbiters may not work hand in hand with life, for that will ruin them.

Appearances
Arbiters can generally be male or female and can come in different shapes, sizes, and appearances. However, all of them appear to be inclined to wear uniforms. The uniforms mainly consist of a pair of black pants with black dress shoes and a matching black vest with a plain button up dress white shirt underneath and a red bow tie. All of the arbiters also have eyes with cross like pupils.

Job
The main job of an arbiter is to pass judgements on the deceased, and choose whether their souls will be sent for reincarnation or be cast in the void to never be used again. Arbiters have different methods of accomplishing their judgements and it is stated that there are many different ways to judge a human. However, the main structure to judge a human, as enforced by both Nona and Oculus, is to place the humans in an extreme condition to draw out the darkness of their hearts and judge them based on their actions. Many arbiters are shown to do this by telling their guests that they are risking their lives by playing a unique game that will decide their fates. The known games are Death Pool/Billiards, Darts, Old Maid, Air Hockey, Bowling, and Twister. Following the games, the arbiters make their judgements and dismiss the guests to the respective elevators to reincarnation or the void.

Hierarchy
Though not fully explored in the show, there seems to be a hierarchy established for the arbiters. It is clear there are certain bosses and people who are higher up than them. For example, Nona is clearly the boss and owner of Quindecim and Viginti. Oculus is also clearly superior to the arbiters and even Nona, as he has stated he is closest to being God though it remains to be known what he means and he is never seen doing actual work. In episode 7, when Nona inquires Castra to give Decim two special customers, Castra says she can't because they are "marked" and need to be sent to a special arbiter. This would mean that there are certain arbiters that handle certain types of customers and are given these customers direct from the Information Bureau. In a sense, these arbiters are given more "difficult" humans or humans who are horrible, twisted, or have committed some form of grave and terrible sin. Since Decim wasn't supposed to get these customers, it would seem he is a lower level arbiter, possibly since he has less experience. It is unknown if an arbiter can become an arbiter who can handle these customers by gaining experience or if certain arbiters are simply given these jobs from the beginning (though it seems that these arbiters are more experienced so the first theory seems likely).

Existence
Their existence remains a mystery. Nona has stated that they are not human, do not experience emotions like humans do, and have never lived or died. They are even made to look like humans but are created for the specific purpose of judging humans. Oculus reveals that arbiters are made from the mannequin bodies of the deceased (particularly the ones who were sent to the Void). While most arbiters aren't supposed to experience human emotions, some have distinct personalities such as Ginti who clearly has an easily-triggered temper. Decim appears to be an exception to this, as Nona has implanted human emotions in him. Strangely, despite the fact they are not living or dead, they are shown eating food in Episode 7 and they also drink and can taste alcohol, though it remains unknown if food is a source of sustenance for them as it is for humans or if it is simply for their enjoyment, or even where the food comes from. Since items can be transported from the human world to the world of the arbiters like the Chavvot book Chiyuki liked, food could be transported from there but as to how or if it is even necessary to have food is unknown. It could also come from a different unknown source.

Bars
There are several floors in the building the arbiters work and each seems to contain a bar that one arbiter works. It seems only one arbiter is allowed though assistants, whether human or animal, seem allowed. The bars vary in style depending on who the owner is but all include elevators that link the bar to outside and a hallway with bathrooms. There is also a game-board that is used to select the game for the customers to play and what appears to be an extra room where the game is played. The floor for the extra room is equipped with a motorized platform to bring about what game the customers will play. The floor can also change depending on what game they are playing, possibly linking to other dimensions through the use of a remote control which is also used to manipulate the games. Each bar seems to have a latin name associated with the arbiters that run them. e.g., Quin and Decim running Quindecim (15F), Ginti in charge of Viginti (20F) and Nona commanding over Nona Ginta (90F).

Abilities
Each arbiter seems to possess their own set of unique supernatural powers most likely used to keep disobedient customers in line. They vary though all arbiters are expected to know how to deal with alcohol and how to operate the bar to create games. They also receive the memories of the dead as a tool for judging them, though they can request for the memories to be sent to their assistants. Abilities unique to certain arbiters include Ginti's ability to shapeshift and control water, Decim's ability to control threads to grab hold of objects, and Nona's super-strength.

Information Bureau
In addition to traditional arbiters, there is the Information Bureau which collects the memories of the deceased, then compresses them and sends them to the arbiters to help with their judgement. Additionally, those at the Information Desk must check, deliver, and send certain customers to certain arbiters.

Known Arbiters

 * Decim
 * Ginti
 * Quin (formerly)
 * Nona
 * Tria
 * Novem

Trivia

 * Quin is the only arbiter that seems to have been exempted from the first of the Four Rules, as she eventually stopped making judgements and moved on to working in the Information-Processing Bureau.
 * Nona seems to be in charge of all the arbiters that work on floors below Nona Ginta, as she seems to be the boss of Decim and Ginti.
 * Castra has eyes similar to those of an arbiter, though she seems to be working on a different level than the rest of the arbiters, and has more of an administrative position in terms of sending guests to certain bars.
 * Although it is never mentioned or further explained at all in the show, Oculus appears briefly in arbiter attire behind a bar in the opening.