Ango Sakaguchi

Ango Sakaguchi (坂口 安吾,) is a government worker whose ability is Discourse on Decadence. He was close friends with Sakunosuke Oda and Osamu Dazai four years ago.

Appearance
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.

Personality
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 Ability Department, 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.

Ability
Discourse on Decadence (堕落論,) is an ability of unknown nature.

Background
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.

Dazai Osamu and the Dark Era
In the prologue, he met 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.

Later, it is revealed that Ango is a spy from the ministry that worked for the Port Mafia to watch the mafia's activities. Unfortunately, Mori knew this, and used him to spy also on Mimic's movements overseas. This revelation creates a divide between him and Dazai and Odasaku. Consequently, Ango takes his leave from their usual hangout, Bar Lupin.

Main Storyline
Dazai contacted him 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 the each of the Guild members were 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 orcestrated by the Guild. Ango asks him what the price for that is, and Dazai plays innocent, pointing out that the Special Ability Department and the Armed Detective Company always helps each other out. Ango catches on to Dazai's thought process: "The Special Ability Department should also help out in this war." Dazai then says that the Agency wants to rescue Kyouka 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 ask for the Special Ability Department to make the necessary arrangements, and asks Ango if it can be done. Ango confirms this, but tells Dazai that it is only possible if Kyouka 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 Kyouka, 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.

Trivia

 * He appeared as a Dark Era event character for the game 18 (Eighteen)
 * In real life, he is often grouped together along with Osamu Dazai and Sakunosuke Oda as the Buraiha or Decadent School. 
 * In the series, this is often alluded to, because the three used to meet in a certain bar, as seen in Dazai and the Dark Era, and illustrated on the calendar.