Ango Sakaguchi (坂口 安吾, Sakaguchi Ango?) is a government worker from the Special Division for Unusual Powers whose ability is Discourse on Decadence. He was close friends with Sakunosuke Oda and Osamu Dazai four years ago.
He is a tall man with short, dark hair that has the bangs cut so they regularly show his eyebrows, and lightly-colored eyes behind circular framed glasses (though his hair is portrayed as somewhat messier in the anime). His most notable feature is a mole above his lip on the left side of his face.
His normal attire consists of a pale brown double-breasted coat which is buttoned to the left, covering a tab collared shirt with a kobicha brown tie. His pants are the same color as his coat, with his shoes being roughly the same color as his tie.
For the most part, Ango is a composed, calm young man, showing more restraint than Osamu Dazai and more discipline than Oda Sakunosuke. Although he values both as genuine friends, he strongly believes that Dazai needs someone to keep him from acting out as much as he does.
Despite being a spy for the Special Division for Unusual Powers, Ango takes his role as their informant seriously. This includes his efforts recording the lives of deceased mafiosi after the Dragon's Head Rush incident. He records everything from their background to family lives, and makes sure all close relatives are aware of their deaths, but is careful not to let on their connections to Port Mafia. As such, Ango values life a great deal.
When his true intentions are revealed in Bar Lupin, Ango struggles to remedy the strain and tension that arises between him and the other two. However, after being shut down by both Dazai and Oda, Ango respectfully withdraws.
Even after their fallout, Ango continues to respect Dazai, albeit appears even more exhausted by Dazai's theatrics and conniving ways than ever before.
Discourse on Decadence (堕落論, Daraku-ron?) is an ability that allows the user to read the memories left in things, a memory extraction ability.
Despite being useful, this ability can put a considerable amount of mental strain if the user had yet accustomed to it. Ango confirmed this had happened in the past when his brain temporarily surrendered consciousness in order to sort an influx of large information gained from his ability. This ability may also work with humans as seen when Ango offered to read the information sent by Sigma towards Atsushi Nakajima in order to figure out Kamui's location.
Not much is known about his past but it is revealed in the second light novel (Dazai Osamu and the Dark Era) that Ango once worked as Port Mafia's Intelligence Agent, but it was under the Government's orders to spy the mafia's activities. During his time working as an intelligence agent under for the Port Mafia, he also became an agent for Mimic under Mori Ougai's orders.
It was later believed that Ango is not a mere government worker, but instead, the leader of The Seventh Agency, as cited by Mushitaro Oguri, which Ango denied upon his questioning, telling that it was a lie told by Fyodor Dostoevsky.
In the prologue, he meets Dazai and Odasaku in their usual bar, having come from a deal in Tokyo. He shows them the object of the deal, an antique watch. Dazai asks if he has a camera, which he does, and all three take a photo together. The next day, he was reported missing right after he bid farewell to his friends the night before.
Soon enough, Oda locates and saves Ango who was discovered as a spy and had been set up to be killed. It is soon revealed that Ango is also a spy infiltrating the mafia, having come from the ministry that worked for the Port Mafia to watch the mafia's activities. Mori had known about knew this and used him to spy on Mimic's movements overseas, making him a triple spy. This revelation creates a gap between him, Dazai, and Oda. Consequently, Ango takes his leave from their usual hangout, Bar Lupin.
Dazai contacts Ango after 4 years, in the middle of the three-way organization war. Ango, along with two bodyguards, met with Dazai in a carpark. Dazai initially greeted Ango cheerfully, but his real aim was the gun tucked in Ango's waist. Dazai immediately cocked the gun at Ango's head mockingly praising Ango for coming and asking if he actually thinks he has forgiven him. Ango pointed out that he was the one who cleaned Dazai's records, which allowed Dazai to join the Agency and owes him that. Dazai, with Ango's bodyguards aiming to kill him if he moves wrongly, concedes. Dazai also points out that Ango knew that that situation will happen, and so kept his gun without bullets. Dazai then proposes a ride around town in Ango's car, to which Ango agrees.
Ango and Dazai talk about the Guild, and Dazai subtly urges Ango to make a move on them, being the Department that handles Ability Users. Ango then reveals that the Department has been aware of the Guild's activities, along with other specifics regarding the organization, including the fact that each of the Guild members was given a diplomat's level of authority, and thus cannot be touched. Ango stops the car and asks Dazai to run and tell his subordinates in the Agency that they are in danger. At that moment, another car crashes with their car, crushing Ango's side of the car.
Ango is later seen when Dazai visits him in a hospital. Ango is severely injured, head covered in bandages and a cast on his right leg to his foot. Dazai then says that he brings good news: that Akiko Yosano will heal him from the injuries he sustained from the car crash, which turns out to be orchestrated by the Guild. Ango asks him what the price for that is, and Dazai plays innocent, pointing out that the Special Division for Unusual Powers and the Armed Detective Agency always help each other out. Ango catches on to Dazai's thought process: "The Special Division should also help out in this war." Dazai then says that the Agency wants to rescue Kyōka Izumi before the final showdown with the Guild. Ango says that, from what he's heard, Kyouka is being held in a UAV for isolating dangerous Ability Users. Dazai asked for the Special Division to make the necessary arrangements. He asks Ango if it can be done. Ango confirms this but tells Dazai that it is only possible if Kyōka is a member of the Agency, which she isn't, as she hasn't passed the entrance exam. Ango then says that his authority is not enough to grant Kyōka, who is a mass murderer and not a member of the Agency, an amnesty; he instead offers assistance regarding the Agency's operations against the Guild. Dazai prepares to leave, but before letting him go, Ango reinstates their deal and says he won't go back on it then asks a question: "Is there a particular reason why the airbags on my seat were the only ones that malfunctioned when the car came crashing into us out of nowhere?" In reply, Dazai gives him a dark smile.
Ango meets Dazai in front of Bar Lupin in the middle of work. Not long after that, two of his subordinates point guns towards Dazai, accusing him of having brought Tatsuhiko Shibusawa into Yokohama, the person responsible for the Dragon's Head Conflict, a tragedy six years prior the event. A moment later, clusters of fog start to rise around his feet as Shibusawa appears behind him, taking away Dazai.
Ango later contacts Doppo Kunikida, reporting that the fog has engulfed the entirety of Yokohama, disconnecting Yokohama from the outside world and confirms that only the gifted are present after he manages to locate each of them. The fog also causes the gifted to be separated from their ability, thus Ango warns Kunikida and the rest of the Agency to be careful. Ango also requests the Agency to eliminate Shibusawa as the mastermind of this incident and gives them Shibusawa's current location.
In order to defeat the dragon, Ango calls upon Chūya Nakahara, which in turn decided to break into the walls of the government facility Ango's currently in. Chūya blames Ango and the rest of the government bureaucrats having employed Shibusawa six years ago in order to end
all the city's conflict which ends up backfired, creating an even bigger conflict instead. Ango in his defense states that all he did was for the peace of the nation. In exchange for Chūya's assistance, Ango states that he wouldn't mind if Chūya wanted to take his life, Chūya agrees and proceeds to commence the operation.
After the incident finally sorted out, Ango is seen with his subordinate, Mizuki Tsujimura, pulling off their current day four of all-nighter marathon, writing reports upon the incident's aftermath. Tsujimura then asks Ango about his thoughts of the incident which then Ango replies that the incident fundamentally caused out of Shibusawa's isolation and loneliness, probably the results of his extreme intelligence and later states that he couldn't even imagine it to the already sleeping Tsujimura.
Ango is called upon a break-in of the Special Division document transport vehicle, an attacker which then later revealed to be Port Mafia's Kōyō Ozaki has stolen a document with code name I-75-81-A containing a record of the death of Kyōka Izumi's parents.
Ango arrives at the government bank upon hearing that the Armed Detective Agency members, Atsushi Nakajima and Kyōka Izumi, who are currently wanted fugitives manage to infiltrate the facility. Ango immediately requests control over the security forces and begins to search the building. Mushitaro Oguri, upon discovering that the Special Division has surrounded the building, becomes terrified when he discovers that Ango is currently searching the building.
Oguri claims that he heard of Ango before, referencing Ango as a member of The Seventh Agency, a criminal organization created by the government. Oguri uses his ability in order to escape by putting stolen cash above their heads while activating his ability, thus concealing the three of them. They hide in a room and have Kyōka's Demon Snow to close the door of the room next door. This proven effective as Ango and the Special Division troops have fallen for the trick.
Ango examines the floor of the empty room using his ability only to discover there is no single trace of ability having been used. Just as the threesome about to escape through the sewer, Atsushi and Kyōka are struck with tranquilizing darts, leaving them temporarily incapacitated, therefore unable to attack. Oguri, looking evidently perplexed, asks Ango how he managed to discover the three of them. Ango explains about his ability and the fact that he extracts memory from the dropped cash that they have been using to conceal themselves.
But instead of turning them in, Ango pushes them into the sewer, helping them escape. Furthermore saying that Dostoevsky will think that they are against each other, while in fact, he and Dazai have been allies from the start. Upon Dazai's imprisonment, Ango has been acting as his middle-man ever since, decrypting the numerical code from Dazai's vital signs tracker that Dazai sent by manipulating his heart rate.
Ango then explains that he is not a member of The Seventh Agency and the rumors were in fact, one of Dostoevsky's lies that was told to Oguri to prevent them from seeing each other. In Anne's room, he then confesses about having employed the organization once to clear Dazai's crime records so that he can live outside the mafia and warns that the alliance of Dostoevsky and The Seventh Agency will be the worst possible alliance if they were to come together.
- (to Osamu Dazai and Oda Sakunosuke) "The death of a person is not just some number. Every one of their lives must have some meaning."
- Despite being close to both Odasaku and Dazai in the original series, Ango makes no appearance in BEAST - White Akutagawa, Black Atsushi, nor is there any mention of him.
- His real-life counterpart Ango Sakaguchi was born with the name Heigo Sakaguchi (坂口 炳五, Sakaguchi Heigo?). Ango is often grouped together along with Osamu Dazai and Sakunosuke Oda under the buraiha literary movement. This groupment is often alluded to in the series, especially with the trio's nightly meetup in Bar Lupin.