Osamu Dazai

Osamu Dazai (太宰治,) is a member of the Armed Detective Company and was a former Executive of the city's worst underworld organization, the Port Mafia

Appearance
Dazai has mildly wavy, short dark brown hair and narrow dark brown eyes. His bangs frame his face, while some are gathered at the center of his forehead. He is quite tall and slim in physique.

For his attire, Dazai wears a long sand-colored trench coat, the belt of which he leaves untied. Under it is a black vest over a striped dress shirt that is light blue in hue. He wears a bolo tie, which is held by a brown ribbon and a turquoise pendant. He also dons beige pants, dark brown shoes, and has bandages wrapped around his entire body; only his face, hands, and feet are left uncovered. The reasons for the bandages are yet to be discovered.

Back when he was in the mafia, Dazai wore a dark trench coat that reached under his knees. He also wore bandages over his right eye and his right arm is in a sling—presumably products of his suicidal pastimes. At some point, he was able to regain the use of his right arm; the same arm he then used to aim and fire a gun at Akutagawa three times.

Personality
Dazai is a mysterious person, his true intentions are never revealed unless he himself reveals them. The person who got closest to the truth of his personality, as acknowledged by Dazai himself, was his friend Sakunosuke Oda, who said to him, "it can't be found. (...) You should know this yourself. No matter whether you're on the side of killing people or saving people, there will never be anything that can surpass your mind. There is no place in this world that can fill your loneliness. You will linger in the darkness forever."

Dazai is usually called lazy as Kunikida always scolds him for being unproductive and slacking off. Despite that, he has shown a sharp wit, deducing all the unlikely situations that led Atsushi to believe he was being stalked by a tiger when he actually was the tiger in question. He has complete confidence no matter what type of situation he is dealing with, be it combat or simply bad situations he himself created in the first place. In most occasions, Dazai is overly dramatic, he takes most of his actions as a joke, and, although they are very thought out plans, he does not credit himself for most of what he has done.

Aside from his quick thinking, Dazai is the comic relief in the series and at times Dazai's soft side can be seen.

He is a suicide maniac, often trying to commit suicide in comical manners but often times failing. He, in particular, wishes to commit a double suicide with a beautiful woman (a nod to his real life counterpart who tried to commit double suicide with various women multiple times). However, while his suicidal tendencies are initially comedic, they reveal a truly dark deep hole that Dazai has and believes he cannot fill. He believed he could fill this hole and find a reason worth living for if he lived a life of bloodshed and war, but his friend Oda with his dying breath convinced him to choose the good side. He understood that even though good and evil mean little to Dazai, he may become a slightly better person if he were to choose good.

In the past, while he was still suicidal, it was shown to be far less comedic. He even described death as a way to free himself from the oxidizing world but strangely enough, he could not die no matter how hard he tried. In addition, he was extremely brutal and methodical, setting up traps to catch captives alive to torture the of information and often beat Akutagawa for disobeying orders and in order to push him to the limits to improve his abilities. He was extremely confident and was a terrific planner, coming up with long run strategies to subdue his enemies. Oda once noted that there was a saying in the Mafia that the worst thing for Dazai's enemies was the fact they were his enemies.

While in the present he is more lighthearted and comical, he still retains some of his darker personality. He is still able and proficient at coming up with long run strategies though doesn't inform his teammates what they are until the time is right. In addition, he is willing to use dirty means to achieve his goals, such as purposely deflating Ango's car seat airbag when they crashed so Ango would have numerous broken injuries. This forced Ango to cooperate with Dazai for pardoning Kyouka in exchange for having his wounds healed. When Kyouka shows remorse over having killed 35 people, Dazai remarks with a sinister face that something like that is nothing. Nonetheless, he does care for his teammates and watches out for them, especially Atsushi for whom he sees the greatest potential.

Ability
No Longer Human (人間失格,): This allows Dazai to nullify others' Abilities on contact. His Ability relies on skin contact and is always active. As such, he can nullify any Ability even while restrained as soon as it touches him.

Background
Ōgai Mori took in Osamu Dazai and Yumeno Kyusaku as his wards before he even ascended as the Mafia Boss. His past before joining the Mafia is unknown.

At some point, when the former Boss—whose only aim at that time was more death and destruction—was dying, Mori killed the Boss himself, with only Dazai as the witness. He then tells Dazai the cover story: that the Boss died of a serious illness and that his dying wish was for Mori to succeed him. Dazai was 14 years old.

He and Chuuya used to be partners during his days in the Mafia, and together—after they had decimated the entirety of an enemy organization in one night—they became notoriously dubbed as the "Criminal Underworld's Worst Enemy", earning the title Double Black (双黒, Sōkoku).

Dazai Osamu and the Dark Era
During the events of Dark Era, Dazai was one of the five Port Mafia Executives. He was the youngest person to become an executive in Port Mafia history (being considered as an executive before he was even 16 ), and a living legend within the mafia as well—to the extent that there is a saying going around the mafia: "The misfortune of Dazai's enemies is to have Dazai as their enemy". In the years he was an Executive, roughly half of the mafia's overall profits could be solely attributed to him, to the extent that Ougai Mori mentioned that, "Given another four or five years, I wouldn't be surprised if Dazai killed me and took over my position." He was also a specialist at torturing people for information, claiming to Kouyou Ozaki that, "There hasn't been a single prisoner who hasn't spilled everything under my interrogation." . He even gave Akutagawa spartan training in using his Ability, and was the one who gave Akutagawa the idea of cutting space to shield himself.

The trigger for Dazai leaving the mafia was his old friend Oda Sakunosuke, a low-ranked mafia member—who was killed in the conflict between Port Mafia and Mimic, orchestrated by Ougai Mori to obtain an official license from the government: proof of the government expressing silent consent of the Port Mafia's existence and its activities as an organization. Already distraught from the knowledge that Ougai intentionally drove Oda Sakunosuke into a suicidal attack against the enemy commander, Dazai took Oda's last words to heart—"I know it makes no difference to you, but please become a good human being. Save the weak, protect the orphaned. I suppose you don't care for either justice or evil...but striving to be a better person is a wonderful thing"—and decided to leave the mafia. He was 18 years old.

It is stated by Akutagawa that, during a mission, he suddenly aborted it and supposedly, defected from the Mafia. Dazai later tracked down Taneda Santouka, who was the acting commander for the Japanese ministry's Special Abilities Division and requested to work in a place where he can help people. Taneda initially thought that Dazai wanted a position in the Special Abilities Division, and so expressed hesitancy, but Dazai said that he does not do well in a place with too many rules. Taneda then recommended the Armed Detective Company to Dazai, on the condition that he'll need at least two years laying low to cleanse his past. Later, it was his friend, Ango Sakaguchi who assisted him with that. It is unknown what he was doing during those two years, but it is mentioned by Dazai himself (though the extent of the truth of the matter is unknown) that before meeting the Armed Detective Company, he was an unemployed and unmotivated and drunk in a bar that he used to frequent

Dazai Osamu's Entrance Exam
At the age of 20, he joined the Armed Detective Company under recommendation from Chief Taneda of the Ministry of Internal Affair's Special Ability Department, and—as a newbie—was entrusted by Fukuzawa Yukichi to Doppo Kunikida, along with administering his entrance exam. Shortly after, they were both assigned to work on the Serial Disappearance of Yokohama's Visitors Case, which Kunikida decided to be Dazai's entrance exam.

Plot
Dazai first appeared floating down a river, apparently trying to commit suicide until he was accidentally found by a starved Atsushi. Afterwards, he and his colleague, Kunikida treated Atsushi to food while listening to his story about how he ended up at the river while hungry. He then introduced himself and Kunikida as part of the Armed Detective Company and they would like to hunt down the tiger that is apparently following Atsushi and terrorizing the areas wherever he went.

At night, while Dazai and Atsushi waited for the tiger to show up, he realized all of the clues that led Atsushi to be confused about the tiger was matching up to be the fact that Atsushi actually was the tiger. As Atsushi lost control of himself and transformed into a full-grown tiger, he was easily subdued by Dazai's ability, No Longer Human, and lost consciousness. Dazai then brought Atsushi back to the dorm where the Agency members are staying. The next day, he called Atsushi for help because he was stuck in an oil barrel trying to commit suicide and gives him the address of the Agency at the same time.

Quotes

 * (to Oda Sakunosuke) "Success is harder than failure for many things in this world, right? (...) That means I shouldn't place suicide as my goal, but rather, attempted suicide! It may be harder to succeed at suicide, but to fail at attempted suicide should be easier!"
 * (when asked how he got a few of his injuries by Oda) "I was reading a book titled 'How to Prevent Accidental Injuries' while walking when I accidentally fell into a ditch. (...) I was speeding on a mountaintop when I fell into a precipice. (...) I was trying out this suicide method of hitting one's head on the corner of tofu."
 * "Disputes that become worse because of me... how wonderful."
 * "You're an idiot, Odasaku, you're a big idiot! (...) To accompany this sort of guy into death, you're an idiot!"
 * (after eating a hallucination-causing mushroom) "Hohohohoho, as expected, The Complete Suicide Manual is a masterpiece! Just by eating the mushrooms growing on the mountain trail behind, I am able to go down such a happy and pleasant road towards suicide! (...) Hey, hey, Kunikida-kun, come on over to the Underworld too! Look, the alcohol are free-flow, there's endless food, and you can smeel the pretty ladies all you want! (...) Wow! Kunikida-kun, there's a gigantic sea anemone outside the window! Banana! It's eating a banana! It's taking away all the white party blowers around us! (...) I get it! I'll strip; if I strip, the viewers' ratings will go up! It's not an easy task but let's strip, then as a change, let's put on full-body tights! Everyone wearing tights, going to the bank, then dancing the Cossack Dance! (...) There's a voice... urgh, he's—he's inside my head!... A small gramps! And he's whispering to me to go to Kyoto, there's an authentic tofu with a unique flavor that I have to tr—"
 * "... could it be that you're afraid, Mori-san? That one day, I would slit your throat and take over as the Boss? Like what you did to your predecessor?"
 * "Man fears death and yet, at the same time, man is drawn to death. Death is endlessly consumed by man in cities and in literature. It is a singular event in one's life that none may reverse. That is what I desire."
 * "Anything I would never want to lose will be lost. It is given that everything that is worth wanting will be lost the moment I obtain it. There's nothing worth pursuing at the cost of prolonging a life of suffering."

Trivia

 * Dazai's past with Fyodor Dostoyevsky likely refers to the influence Crime and Punishment had on Ōba, the protagonist of No Longer Human.
 * He, along with several other characters, made an appearance in the mobile game Love Heaven as a limited time character.
 * He and several other characters also made an appearance in the mobile game Kimito Lead Puzzle 18 as a limited time character.
 * He and several other characters made another appearance in the mobile game Yumeiro Cast as limited time characters.
 * His constant attempts to commit suicide with a beautiful woman could be an allusion to his real life counterpart's attempted double suicide with Shimeko Tanabe and Hatsuyo Oyama. His attempt with his lover Tomie Yamazaki was ultimately successful.
 * It's also possible that his suicide attempts serve as a reference to No Longer Human 's protagonist Ōba Yōzō's multiple suicide attempts throughout the story, which is considered to be a reflection of Osamu Dazai's turbulent life.
 * He was the youngest Executive in Port Mafia history.
 * In real life, he is often grouped together along with Sakaguchi Ango and Oda Sakunosuke 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.
 * Dazai usually refers to himself by the gender neutral pronoun, "watashi," rather than the more masculine pronouns like "boku" or "ore." This is likely because of the format of traditional I novels, which the real Dazai specialized in, typically used formal "watashi" pronouns over its variants.
 * Dazai is very bad at driving, as shown in the first light novel "Dazai Osamu's Entrance Exam".
 * His type is any woman who would like to do suicide with him.