Honestly, if you’ve spent any time in the Bungo Stray Dogs fandom, you know that timelines are a bit of a mess. People argue about power scales and ship dynamics, but one question always pops up in the middle of the chaos: how old is Akutagawa BSD actually? It’s not just a trivia point. Knowing his age changes how you see his desperate need for Dazai’s approval and his rivalry with Atsushi.
Ryunosuke Akutagawa is 20 years old.
He’s not a teenager, even though his lean build and the way he lashes out might make him seem younger. He’s also not quite a "grown man" in the way characters like Fukuzawa or Hirotsu are. He’s in that weird, volatile transition period.
The Exact Breakdown of Ryunosuke Akutagawa’s Age
Let's get the facts straight. Akutagawa was born on March 1. If you’re into astrology, that makes him a Pisces, which is funny considering how much he hates "weakness" and emotional vulnerability.
In the main timeline of the anime and manga, he is consistently 20. But because Bungo Stray Dogs loves a good flashback, we’ve seen him at a few different stages.
✨ Don't miss: Who was the voice of Yoda? The real story behind the Jedi Master
- The Slums (Childhood): We don't have an exact number for the very beginning, but he was a young boy living in absolute poverty with his sister, Gin.
- The Dark Era (Age 16): This is when Dazai was his mentor in the Port Mafia. If you go back and watch the Dark Era episodes or read the Dazai Osamu and the Dark Era light novel, Akutagawa is a 16-year-old kid. He was already coughing his lungs out and using Rashōmon to tear people apart back then.
- Present Day (Age 20): This is where the majority of the series takes place.
It's wild to think that he's only two years older than Atsushi (who is 18). That small gap makes their "New Double Black" dynamic feel way more like a sibling rivalry than a mentor-student relationship.
Why He Looks and Acts the Way He Does
You might be wondering why a 20-year-old man looks like he’s one bad day away from collapsing. It’s not just the aesthetic. Akutagawa is canonically sickly. He has a chronic lung ailment—likely a nod to the real-life author Ryunosuke Akutagawa, who struggled with health issues—which gives him that pale, fragile appearance.
He stands at 172 cm (about 5'8") and weighs only 50 kg (110 lbs).
That is incredibly thin for someone his height. His physical state makes his combat style even more impressive. He isn't using muscle; he's using raw, terrifying Ability power and sheer stubbornness to stay standing.
🔗 Read more: Not the Nine O'Clock News: Why the Satirical Giant Still Matters
The BEAST Timeline Confusion
If you’ve dipped your toes into the BEAST light novel or movie (the "what if" universe where Akutagawa joins the Agency and Atsushi joins the Mafia), the age thing gets a little murky for fans.
Don't let the different outfits fool you. In the BEAST timeline, the ages generally stay the same relative to the events. The story takes place roughly four and a half years after Akutagawa’s first meeting with Dazai. Since he was around 15 or 16 when they met, he’s still roughly 20 by the time the main BEAST conflict reaches its peak.
The Dazai Factor: Why 20 is a Loaded Number
The most important part of how old is Akutagawa BSD isn't the number itself, it's the gap between him and Dazai.
Osamu Dazai is 22.
💡 You might also like: New Movies in Theatre: What Most People Get Wrong About This Month's Picks
That means Dazai was only 18 when he was training a 16-year-old Akutagawa. Think about that for a second. An 18-year-old was the "adult" in charge of a traumatized kid's life. It explains a lot about why their relationship was so toxic and broken. Dazai didn't know how to be a mentor because he was barely out of childhood himself.
By the time Akutagawa is 20, he’s spent four years chasing a ghost. He’s spent a fifth of his entire life trying to prove himself to a man who is only two years older than him. When you look at it that way, Akutagawa's character feels a lot more tragic than just "the guy who coughs and kills people."
Surprising Details Most Fans Miss
Most people just check the wiki and move on, but there are some nuances to Akutagawa’s age and development that the story hints at:
- The "Vampire" Complication: Without spoiling too much for the anime-only crowd who haven't caught up to the later seasons, Akutagawa's "age" effectively pauses during certain supernatural events. When your body is modified or under the control of an Ability like Bram Stoker's, biological aging isn't really the priority.
- Gin’s Age: His sister, Gin, is actually younger than him. While her age isn't explicitly shouted from the rooftops, she's generally accepted to be around 18 or 19. Akutagawa has been the "adult" and protector since he was a literal child in the slums.
- The Real Author Connection: The real Ryunosuke Akutagawa died at age 35. Fans often speculate if the fictional Akutagawa is on a similar "fast track" due to his illness and the high-fatality nature of the Port Mafia.
What This Means for You
If you're writing fanfic, drawing fanart, or just trying to win an argument on Twitter, keep that "20" in your head. He’s a young adult who never got to have a childhood. He’s a man who has the weight of the Port Mafia on his shoulders but the emotional maturity of someone who stopped growing the moment Dazai hit him in that forest.
To get the full picture of Akutagawa's journey, you should definitely check out the Bungo Stray Dogs: Heart of Akutagawa or the Fifteen light novels. They provide the context for how he became the "Silent Dog" of the Mafia long before he reached the age of 20.
Keep an eye on the manga's current arc, as character ages might finally start to shift if we ever get a significant time skip, though Kafka Asagiri tends to keep the timeline pretty tight.