Ango Sakaguchi

Ango Sakaguchi (坂口 安吾,) is a government worker whose ability is Discourse on Decadence.

Ability
Discourse on Decadence (堕落論,)

Background
Not much 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.

Plot
Ango appeared in the second light novel as a supporting characters. In the prologue, he met Dazai and Odasaku in their usual bar, and 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 Port Mafia to spy the mafia's activities. Unfortunately, Mori knew this, using him and the Mimic's (a group of ex-soldiers led by Andre Gide) conflicts with the ministry to get the Ability Business Permit.

Trivia

 * In real life, he is often grouped together along with Osamu Dazai and Sakunosuke Oda as the Buraiha or Decadent School. 
 * And on the series, this is often alluded, because the three used to meet in a certain bar, as seen in Dazai and the Dark Era, and illustrated on the calendar.