He was a tall man with rust-red eyes and reddish-brown hair which was slightly parted so that a small area of his forehead was visible. He also had light stubble similar to Mori's.
His attire consisted of a black-and-white pinstriped collared shirt which he wore loosely, as the collar covers part of a long-sleeved beige brown coat with brown buttons on the cuffs. His pants were pale grey, whilst his shoes were light brown.
In BONES' anime adaptation, his eyes were a cool blue. His collared shirt was also simplified to a solid black, and his pants were a pale green.
Oda was a man described as kind, despite working for the mafia, by Dazai during the events of Chapter 34, while he reminisced his friend during a conversation with Kyōka. He had a nice temper, and so, was one of the few persons in the mafia who seldom killed. Nevertheless, when furious, he showed amazing and strong fighting skills that Dazai had warned Akutagawa about. Dazai called him "a man who has no ulterior motive". Oda means what he says, and sometimes mistakenly assumes that about other people—for example, when he gave serious responses to Dazai's joke explanations of how he got his various injuries.
However, he also had an incredibly perceptive side to him that allowed him to come the closest to understanding Dazai, whom he referred to as "his dear friend, who had grown tired of the world and is simply waiting to die." It is his understanding of Dazai's loneliness, as well as his regret of not being able to do anything about it, that prompted him to leave behind the last words that became the trigger for Osamu Dazai deserting the mafia in favor of carving a brighter path for himself, something that Oda wanted to do.
Flawless (天衣無縫, Ten'imuhō?) is an ability that allowed Oda to predict 5-6 seconds into the future.
It is an extremely powerful ability that renders most surprise attacks useless, as Oda can see them coming 5 seconds before. However, it has its limitations. For example, since Oda can only see 5-6 seconds ahead, if the time between triggering a trap and Oda realizing that he's in danger is longer than 5-6 seconds, then Oda wouldn't be able to use his ability to save himself and 'un-trigger' the trap.
The future that Oda sees with this ability is also limited to his current decision. If he decides to change his actions based on the vision he sees, then he'll see another future play out - one that might reveal another danger that he wasn't able to see before, and it may be too late to avoid it at that point.
As what is shown in the light novel "Osamu Dazai and the Dark Era", Oda Sakunosuke is a member of the Port Mafia. He used to be an assassin for hire and was ruthless in his line of work. However, his meeting with Sōseki Natsume in a cafe changed him. Natsume caught Oda reading the first two volumes (out of three) of a novel he salvaged from one of his recent victims' houses, and commented that the last volume is an atrocious piece of work and Oda should be happy that he only has the first two volumes. Natsume encouraged Oda to write his conclusion to the novel, and later gave Oda the last volume of the series but with the final pages missing.
"To write novels is to write about humans"—Oda took Natsume's words to heart, and, believing that a murderer has no right to write about human lives, decided to never kill again in hopes of becoming a novelist eventually and writing his conclusion to the book in a room with an ocean view. He also strived to be a better person in general (a piece of advice that he would later give to Dazai Osamu), adopting five children that were orphaned as a result of particularly intense conflict between underworld organizations. He became somewhat of an oddball in the mafia, known as 'the mafia member who doesn't kill'.
After the Dragon's Head Rush conflict, he took in 5 children, four boys, and one girl: Kousuke, Katsumi, Yuu, Shinji and Sakura, children who were orphaned after the incident. He mostly leaves them in the care of a curry shop owner. He visits often and the children are fond of him. He leaves money to the shop owner to support the children.
The Untold Story of the Founding of the Detective Agency
Sakunosuke was hired to supposedly kill a certain lady, a company president, but was framed up by the president's secretary.
He was captured and put in a room adjacent to the office with both his hands and legs tied to a chair and a sack over his head. His belongings are laid out in a table behind him. Fukuzawa Yukichi was the president's hired bodyguard, and, after taking the knowledge that his client had died by being pushed off her office window, he came to see the scene of the crime and the captured assassin. Fukuzawa decides to test just how good Sakunosuke as an assassin. Picking up a pen from Sakunosuke's belongings, he sends out killing intent together with quick-drawing the pen (like a sword) at him. Sakunosuke successfully dodges even without seeing what Fukuzawa was doing by moving sideways, making himself topple on the floor, still tied on the chair; this impresses Fukuzawa and he makes the deduction that Sakunosuke is no ordinary assassin, and must have been paid a high sum of money.
After Ranpo Edogawa comes in the office looking for employment and ends up revealing bit by bit to Fukuzawa how the secretary did the murder, Sakunosuke makes his move and undoes the binds on his legs, enabling him to move around. He and Fukuzawa had a short crossing of blows, but Sakunosuke eventually successfully gets a hold of his gun. At that moment, Fukuzawa realizes who his opponent was, but before he can stop Sakunosuke, he has shot the secretary dead—all that with a sack over his head and his hands still tied behind him. Fukuzawa was distracted for a moment with the dead secretary, and that was when Sakunosuke made his escape.
Dark Era Arc
Sakunosuke was first seen drinking in Bar Lupin with Osamu Dazai and Ango Sakaguchi. The three of them converse like old friends, an odd sight considering their respective positions in the mafia—Dazai, one of the five executives; Ango, an intelligence member; and him, a low ranking member who is only assigned the most trivial of tasks due to his refusal to kill. After some idle chatter, they say goodbye for the night, but not before Dazai convinces Ango to take a photo of the three of them to commemorate their friendship.
He was called out by Mori a few days later. The leader of port mafia informs him that Ango had gone missing ever since that night, and tasks Oda with tracking the man down. Though confused at Ougai's choice of assigning him that mission, he nonetheless sets out to investigate Ango's room. During his investigation, he was assaulted by members of Mimic, an organization that is seeking to wage war against Port Mafia and discovers an old gun hidden in Ango's room - the same model that identifies Mimic members. Dazai also comments that Ango was lying about what he did on the day the three of them met up at a bar - further increasing Oda's suspicions.
Distraught at the possibility of Ango being a double agent for Mimic, he goes to visit the five orphans he adopted. Seeing them happy and well reassures Oda a little, and reaffirms his decision to leave the mafia as soon as the children were grown enough to support themselves.
Later, he receives a call from Dazai. The Mafia had discovered new clues about where the Mimic members may be hiding, and Dazai urges Oda to go and watch the location first. However, Oda decides that he wanted to investigate the building before Dazai and his subordinates came, in fear of them finding more damning evidence against Ango. He founds Ango in the building, bound to a chair next to a time bomb. Oda hauls Ango out of the building and barely manages to escape the explosion unscathed. At this point, Oda had figured out that Ango wasn't a double agent for Mimic - but a double agent for the Mafia. He disappeared because his status as a spy was revealed to Mimic. Ango tells Oda some information about Mimic's commander - a man named Gide - but soon left with a group of black-uniformed men that were neither Mimic nor the mafia (later revealed to be part of the Japanese ministry's supernatural division). Oda was not able to give chase as he triggered a slow-acting poison trap that knocked him out.
He wakes up in a hospital room, having been recovered by Dazai's subordinates when they reached the building. Dazai informs him that several Mafia members (including Akutagawa) are in open conflict with Mimic members in front of an art museum. Oda is quick to rush to their aid and saves Akutagawa from being killed by Gide- the commander of Mimic who shares Oda's ability to see a few seconds into the future.
Delighted to find someone who shared his ability, Gide tries to provoke Oda into fighting and eventually killing him. Gide and his organizations were former soldiers betrayed by their own country, and are now seeking to die amid the thrill of battle. However, Oda refused to kill Gide due to his personal beliefs. Gide retreated in fury, but promised to "make Oda understand him".
After the battle, Dazai takes Oda to a place where they could find Ango - the bar that the three of them used to frequent. Dazai had correctly deduced Ango was neither a spy for the mafia or Mimic - rather, he was a triple agent sent by the Japanese ministry's supernatural division to keep an eye on the port mafia. Ango divulges some intelligence regarding Mimic to Dazai and Oda, sharing one last drink with the two of them while lamenting their lost friendship. With Ango's identity revealed, there was no possibility of the three of them staying friends with the existing conflicts of interest. The atmosphere was somber as Ango left for good, leaving behind the photo they took the last time they were together.
Afterward, Dazai tightens the security around Oda, as well as the people close to him, including hiding away his five adopted children in a mafia safe house. However, that was all for naught as the Mimic members managed to kidnap the children and kill them all in an explosion right before Oda's eyes. Pushed over the brink of despair, Oda decides to go back on his principle of not killing and take revenge on Mimic. Later on, this was all revealed to be part of Mori's plot (he was the one who told Mimic the location of Dazai's safe house) to provoke Oda, the only person who could counter Gide's future sight, into destroying Mimic.
Oda killed for the first time in years, taking down the vast majority of Mimic's remaining forces by himself. He proceeds to engage Gide in a fierce battle that resulted in both of them killing each other but not before reaching a level of understanding because of their similar abilities. The two of them reveal to each other their pasts and what drove them so far, and though the battle ended up with both of them dying, they earned each other's respect and experienced a sense of satisfaction after the battle.
Dazai, who had at that point figured out Ougai's entire plan, hurried to Mimic's base to save Oda. However, he only made it in time to witness Oda's final moments. With his last words, Oda tells Dazai what he had understood of the man - that Dazai will never be able to find anything to bury his loneliness, nor anything that could exceed his expectations. But if neither justice nor evil made a difference to him, Oda wanted Dazai to be on the side that saves people - something that he set out to achieve before his life was cut short. Oda dies with a smile, knowing that he'll soon see the five children he adopted again.
- "The last book in the series was wonderful, but there was one flaw. Several pages had been cut out and removed toward the end. Right before the removed section, there was this line: "People live to save themselves. You will understand that at the moment of your own death."
- "I have one regret. I did not say farewell to my friend. To the man who was my only friend in this world which I live in. He seemed to have tired of this world and was waiting for death."
- (To Dazai) "Listen. You told me that you might find a reason to live if you lived in a world of violence and bloodshed. You won't find it. You must know that already. Whether you're on the side who kills people or the side who saves people, nothing beyond what you would expect will appear. Nothing in this world can fill that lonely hole you have. You will wander the darkness for eternity. (...) Be on the side that saves people. If both sides are the same, become a good man. Save the weak, and protect the orphans. Neither good nor evil means much to you, I know... but that'd make you at least a little bit better. (...) Of course, I know. I know better than anyone. Because... I am your friend."
- "People exist to save themselves, huh... How true..."
- If Odasaku was still alive, he would have been 27 years old.
- In real life, he is often grouped with Osamu Dazai and Ango Sakaguchi as the Buraiha or Decadent School.
- Furthermore, in the series, this often alludes because the three used to meet in a certain bar, as seen in Osamu Dazai and the Dark Era and illustrated on the calendar.
- His favorite food was curry rice by the shop Freedom (In, reality Oda Sakunosuke likes curry so much he wrote an article about it). An autographed photograph of Oda hangs in the Osaka restaurant Jiyūken (自由軒). Jiyuuken happens to be the name of the curry rice Oda favors; it is spicy curry rice with a raw egg on top of it (as what the anime showed).
- It was recently revealed that Oda's height is 185 cm (as of Dark Era).
- He appeared as an event character for the Dark Era collaboration with the game 18 (Eighteen) and Love Heaven.
- His type is a tactful woman (source: 2nd Season Guidebook).
- He also made an appearance in Kanaineco's Bungou Stray Dogs Wan! for the special chapter Dark Era and a bonus of one of the Young Ace's series.
- It is very likely that's the book he was reading was Kokoro. This is because it is split into three parts, and it was written by Natsume Souseki like the book Odasaku was reading.
- Dazai Osamu and the Dark Era - page 424