Sigma

Gender
Male
Birthday
Unknown
Age
Unknown
Height
177 cm (5'9)
Weight
62 kg
Blood Type
Unknown
Likes
Casinos, high places, talent, cookies
Dislikes
Deserts, hunger, people who seek to use him
Ability
Information Exchange Ability (unnamed)
Occupation
Decay of the Angel member (former)
Casino Manager
Affiliation
Decay of the Angel (former)
Sky Casino

Sigma is a young man with long straight hair that reaches his waist. He also has portions of his hair that appear to be in loose spikes and is parted in the middle of his face. The color of his hair's left side is lilac and the right side is white. His eye color is greyish. He also wears earrings on both of his ears. He is seen wearing a long white coat with black pants. His coat has a sparkly or galactic design on the interior.

He appears to be kind to his customers at the Sky Casino, given the fact that he gave a customer another chance by saying that the game is invalid.

He also appears to have a strong sense of ownership. In a conversation with Teruko Okura to close the casino, Sigma refuses and even asks her who will reimburse the revenue and reputation if the casino were to be closed and claims that the casino is his life and his customers are valuable to him.He acts confident and composed even at times of crisis in front of his staff, giving the impression that he's the perfect casino manager and a capable leader. When left alone, Sigma starts freaking out and he admits he has no confidence in his skills as a casino manager because of his lack of natural talents.[5]

Because he has no memories, no family, and no friends, Sigma's greatest wish is a reason to live. He was also described as implacable by Fyodor Dostoevsky since Sigma is a desperate man.

Main article: Information Exchange Ability
His ability allows him to exchange information with anyone he touches. The exchange consists of "giving" the personal information they want to know and thus giving Sigma the information he wants to know.

Leadership skills: As the manager of Sky Casino, he is able to delegate and order tasks properly among his subordinates including taking care of their customers.[5]
Memorization: Sigma can memorize the names of traits of his customers, even up to 20, 000 guests. However, it is revealed that he memorize the knowledge of the Sky Casino and his guests since he didn't want to lose his casino

Sigma himself was a person born from being written into the Book. When he first opened his eyes and became aware of his surroundings, the first thing that greeted him was not a midwife or a mother but a vast desert filled with nothingness, and his only possession were the clothes on his back and a train ticket from a station that does not exist.

Confused with his circumstances, he wandered around the desert nothingness until he was eventually captured by an armed group and held prisoner, where he eventually unlocked his Gift, causing his captors to then take advantage of his ability for their gain during his time with them. Eventually, he managed to escape from then and continued to wander the world nihilistically due to not knowing his reason for living or existing.

At one point, Sigma was approached and invited by Fyodor to join the Decay of the Angel. Upon agreeing, he was eventually given the duty of overseeing the Sky Casino, a job he came to love due to it giving him a sense of purpose.[1] Somewhere along his time together with the Decay of the Angel, he eventually obtained information on the location of the "page" of the Book after meeting and attacking Special Division for Unusual Powers director Santōka Taneda using his ability, though he claims that his attack was a mere threat and that he had no intentions of harming him.

It is a high-altitude floating establishment built right after the war ended. It has helium and the centrifugal force from the mass balancer makes it possible to stay aloft with far less fuel than it appears to need.

It is a de facto free state which indicates it is outside of the jurisdiction of any nation under international law.[1]

Each customer in the casino seems to have a designated code for them.[2] Below are some customer names and their codes:

Code A4098 - has anxiety
Code B9812 - loves gambling
#E2988 - has a heart condition
#N2480
Locations
Central Communications Room
Radio Room
It was written on to "the page" and immediately appeared, together with its 13 years of history. The Sky Casino is made for two goals - a) base for Decay of the Angel’s next terror attack and b) payment for the use of Sigma’s ability.

leader
Kamui
Members
Bram Stoker
The Decay of the Angel was a terrorist organization that has long since been hiding in Japan, operating as a murder association[4] which possesses a single page from the Book.[5] Mushitarō Oguri explains that the Decay has a fourfold scheme with the penultimate goal of eliminating the country, which they operate on by writing on both sides of the page.
Fyodor Dostoevsky
Nikolai Gogol
Sigma

Cannibalistic Mutual Destruction Operation[7]
The plan begins with Fyodor's Rats in the House of the Dead first launching the Cannibalism virus that almost plunges Yokohama's Armed Detective Agency and Port Mafia into a blood battle with their respective leaders' lives on the line. The first stage ends with Fyodor's arrest[8] and the rewarding of the Agency by the government with the Shikyuu Award that acknowledges their contributions to Yokohama.
Armed Detective Agency Frameup
A month after laying low momentarily, Gogol makes the Decay of the Angel's presence known to the Armed Detective Agency through brutal, horrific murders of four government officials within a single week. As horrific as they are, they are symbolic of the Buddhist Cycle of Existence. Having shown four of the five "angels", the Agency deduces that a fifth murder will soon take place.[4] This sets up the Decay's second stage, which is to frame the Agency as a terrorist organization.[5][9]

With the Decay's intelligence and abilities, Gogol also succeeds in infiltrating and impersonating government members of the Special Division for Unusual Powers, securing intel and cover-ups of deeper details of their actions later uncovered by Ango Sakaguchi. Even so, they've manipulated and swayed members, including the Ministry of Justice's vice minister Tonan, and likely several others.

After Gogol captures Mushitarō and the Decay holds him in their clutches, Mushitarō’s ability stops working. Evidence of several hundreds of crimes come to light, especially those of the Port Mafia. This leads to the arrest of Osamu Dazai over his days as a Mafia executive. Moreover, with their hold over several government departments, the Decay of the Angel targets the Armed Detective Agency's downfall and total destruction.

Eventually, Gogol holds Tonan and various government officials hostage, an incident that goes awry for the Armed Detective Agency due to the power of the Book. The Agency is identified and successfully named as the terrorist Decay of the Angel. Concurrently, Sigma meets up with and attacks the Special Division director Santōka Taneda. Using Sigma's ability to exchange information the Decay wants to know most with information their enemies want to know most—that is, a trade of vital information—the Decay consequently acquires information on the Book.[5]

This results to the Agency getting hunted for arrest by the military police and later, the government's elite hunting forces, the Hunting Dogs.[10] At this point, Gogol is supposed to have died to achieve "total freedom" as originally planned, but he deviates from the plan and fakes his death in secret using his Ability, later enlisting Sigma's help to know Fyodor's Ability and killing him for his own personal plot.
Coin Bomb Terrorism
Later, Sigma is questioned in the Sky Casino by Hunting Dogs.[12] This transpires into an airborne battle, which results in the Hunting Dogs witnessing Agency members and allies saving Sigma from falling and eventually, Sigma's surrender.[13][14] Various explosions throughout the world are soon reported to be caused by the circulating coin bombs from the Sky Casino, which marks the third stage of the Decay's plan.[11]

As the world takes notice of recent events, various foreign VIPs gather in Standard Island to forge an international corps to combat global terrorism, which is to be led by the legendary war hero and Hunting Dogs commander Fukuchi.[15] However, Fukuchi's hidden persona as the Decay's boss is soon unraveled by Ranpo Edogawa,[16] and Kamui soon admits that his motive is to take down all nations to bring an end to all wars,[17] which is to be preceded by eliminating the country.

Vampire Infection Outbreak
In order to do so, Fukuchi awakens the undead Bram and uses his infection-type ability to turn others into vampires.[18] The infection spreads from the Mafia all throughout foreign nations, including the Republic of Nalis, amounting to a total of 16 armies being ordered through the infection virus to disarm themselves.

As word reaches the United Nations about Nalis' withdrawal from their security council (along with various other nations), the United Nations secretary-general decides to contact the Order of the Clock Tower into sending in the ability weapon, One Order.