Work Text:
The Armed Detective Agency was unusually quiet for a Tuesday morning. That should’ve been the first red flag. Kunikida sat at his desk, adjusting his glasses and jotting down a detailed itinerary for the day—case reports, training drills, lunch exactly at 12:30…
Then the door burst open.
“Morning!” came a breathless voice. Yamada-san, a fellow government worker and friend of the Agency, stood holding a wiggling toddler in one arm and a large diaper bag in the other.
Kunikida stiffened.
“Oh, Kunikida-san, thank god you're here!” Yamada rushed in. “There was an emergency at work and my sitter canceled last-minute. Can you watch Daichi for a few hours? Just until 3PM!”
“Wh—me?” Kunikida nearly dropped his pen. “I—No! I mean—shouldn’t there be a more… qualified adult?”
Daichi, the toddler in question, clung to Yamada’s jacket like a sleepy koala. His large eyes blinked up at Kunikida, and—like a missile—his small arms suddenly reached out.
“Up!” Daichi said.
Kunikida stood frozen. “I don’t… I’m not…”
Before he could even finish, Daichi latched onto his tie and yanked.
“Waaaaah!”
“Okay! Okay—Stop pulling, please—!”
Behind him, Dazai snorted.
Kunikida turned sharply. “You.”
Dazai blinked innocently from his chair, swinging one leg over the other. “Me?”
“You owe me for taking your paperwork last week. And for eating my bento. Twice.”
“Now, now,” Dazai drawled, already standing up. “I’m not exactly a child-friendly type, Kunikida. What if I inspire the kid to yearn for death?”
Daichi looked at Dazai. Tilted his head. Then giggled.
Dazai stared.
Kunikida stared.
“...Alright,” Dazai said slowly, holding out his arms. “Come here, little curse.”
To everyone’s shock, Daichi waddled over and raised his arms. Dazai picked him up, handling the child like he was some fragile, ticking bomb. Daichi just patted his face and smiled.
“This is horrifying,” Kunikida muttered. “He likes you.”
“Alright, Daichi,” Dazai said, setting him down on the couch. “Rule number one of being in the Armed Detective Agency: if you find a grenade under the table, you don’t eat it.”
Kenji popped his head in. “Did I hear grenade?”
“It’s a metaphor, Kenji,” Dazai replied calmly, while Daichi tried to stick a pen in his ear.
“No, it’s not,” Kenji mumbled as he walked off.
Yosano chuckled from behind her medical desk. “Did Kunikida seriously leave the kid with you?”
“Oh, he begged me,” Dazai said sweetly, pulling Daichi into his lap. “And look, he hasn’t cried once.”
“That’s concerning,” she muttered, but secretly smiled.
Daichi babbled something incoherent and reached for the bandage on Dazai’s arm. Dazai pulled his sleeve back instinctively but paused when the kid just stared at the scars in silence.
“Do they hurt?” Daichi asked, so quietly it caught Dazai off guard.
He blinked.
“No,” Dazai said gently. “Not anymore.”
Daichi nodded seriously, like he understood. Then leaned forward and pressed a sloppy kiss to the old scar on Dazai’s wrist.
Dazai froze.
“…You’re a strange little thing,” he murmured, ruffling the child’s hair.
“Alright, Daichi,” Dazai said, crouching to the toddler’s eye level. “You’ve officially been promoted to Junior Detective.”
Daichi, who had jammed a crayon into a stapler five minutes ago, looked up with wide, sparkling eyes.
“Detective?” he repeated in awe.
Dazai gave a firm nod. “Yes. But before you can solve real mysteries, you must first pass… The Great Agency Trial.”
Kenji poked his head into the room, holding a rice ball. “Is that a new training program?”
“No,” Kunikida said flatly from behind his newspaper. “It’s Dazai wasting time again.”
“Oh, I wanna try!” Kenji said, already chewing excitedly.
Dazai clapped once, gathering everyone's attention. “Your mission, Junior Detective Daichi, should you choose to accept it: retrieve the missing case file that mysteriously vanished from this very room.”
Daichi gasped. “Stolen?!”
“Precisely,” Dazai said with mock gravity. “We suspect… a traitor lurks among us.”
“Hey!” Tanizaki shouted from his desk. “I didn’t take anything!”
“I didn’t say it was you,” Dazai smirked. “But now we know who’s feeling guilty.”
Daichi leaned in and whispered, “Interrogate him.”
Dazai blinked, surprised. Then let out a delighted laugh. “Oh, you’re good.”
He lifted Daichi onto his shoulders. “Detectives, we’re on the move!”
---
Thirty Minutes Later…
Naomi watched as Daichi dramatically pointed toward the bookshelf, where Dazai had—very subtly—shoved the missing file earlier.
“Found it!” Daichi yelled, nearly falling over.
“You really let him solve it?” Atsushi asked, stunned.
“He noticed my footprints on the floor,” Dazai said proudly. “The little guy’s smarter than you.”
“Hey!”
Daichi was then paraded around the office, wearing a paper badge Dazai had made from sticky notes and a paperclip.
“This is… actually kind of cute,” Yosano admitted, as Daichi sat in Dazai’s lap again, drawing what he claimed was a criminal with a funny mustache.
“He named him ‘Kunikida,’” Dazai whispered smugly.
Kunikida twitched.
But as the office filled with laughter, Daichi quietly leaned against Dazai’s chest, exhausted from all the “detective work.” Dazai didn’t move. He gently wrapped one arm around the small boy’s shoulders and sighed, his face softening in a way no one noticed—except Yosano, who paused mid-report.
She watched silently. And for a moment, she swore the faintest trace of something like peace flickered across Dazai’s face.
The Agency had quieted down by the afternoon. Kunikida had retreated to the breakroom with a very large mug of tea, and even Tanizaki had stopped yelling about “not being the traitor.”
Daichi sat curled up on the couch, fiddling with a stuffed tiger Kenji had given him. His eyes were drooping, cheeks flushed with the kind of tired glow only a day of chaotic adventure could give.
Dazai yawned dramatically. “I suppose it’s time for a story.”
Daichi perked up.
“You like stories, don’t you?” Dazai asked, already pulling a book from the Agency’s tiny shelf. “Hmm... The Brave Little Detective. Sounds just ridiculous enough.”
He sat beside Daichi, who climbed into his lap like it was the most natural thing in the world.
Dazai opened the book and began, his voice slipping into a theatrical narrator tone:
“Once upon a time, in the great city of Yokohama, there lived a brave little detective who solved mysteries using his wits, charm, and absolutely zero paperwork.”
“That’s me!” Daichi giggled, pointing to himself.
Dazai nodded solemnly. “Exactly. Now, this little detective had a team—first, there was Atsushi the Bunny Prince—”
“Wait, what?” Atsushi called from his desk.
“—who was brave and noble, but scared of ghosts, loud noises, and Dazai’s driving.”
“Fair,” Kenji said with a nod.
“Then there was Kunikida the Grumpopotamus—”
“Excuse me?” came a very dangerous voice from the hallway.
“—who only spoke in lists and carried around a magical notebook that could summon vegetables.”
Daichi was in tears laughing now.
“But the most mysterious of all…” Dazai lowered his voice to a dramatic whisper. “Was the enigmatic, dashing, death-obsessed mentor known only as… O-sama Dazai.”
Daichi gasped in wonder.
Atsushi covered his face. “Did you just call yourself King Dazai?”
“He wore a coat like no other,” Dazai continued, “and had the magical power of making enemies vanish—and also making paperwork disappear, but no one could ever prove it.”
Daichi clapped, thoroughly enchanted.
By the end of the story, the little detective had saved the city, helped the Bunny Prince conquer his fear of shadows, and taught the Grumpopotamus to smile.
Dazai glanced down to find Daichi resting against him, eyelids fluttering, on the verge of sleep.
“…You’re gonna ruin me, kid,” he muttered with a crooked smile, gently brushing the child’s bangs aside. “You’re lucky you’re cute.”
From across the room, Yosano whispered to Kunikida, “You seeing this?”
Kunikida scowled. “It’s terrifying. He has a heart after all.”
The Armed Detective Agency was unusually quiet—Kunikida had gone to a city hall meeting, Atsushi and Yosano were on a case, and Kenji was fast asleep upside-down on the couch.
Naturally, this meant Dazai had time to do something completely irresponsible.
“Pssst. Daichi,” Dazai whispered, leaning close with a conspiratorial glint in his eye. “You up for a secret mission?”
Daichi dropped his crayon. “Secret… mission?”
Dazai nodded solemnly. “Top secret. Classified. Absolutely forbidden by grumpy mustache men.”
“You mean Mr. Kunikida?” Daichi whispered.
Dazai grinned. “Exactly.”
---
Fifteen Minutes Later...
Daichi wore a bucket hat pulled over his ears and oversized sunglasses Dazai had clearly stolen from a tourist shop. Dazai, meanwhile, was wearing a trench coat over his usual coat, and had smeared chocolate on his cheek for “camouflage.”
“Isn’t this just a snack run?” Atsushi had asked before they left.
“No,” Dazai said, pushing his sunglasses up. “It’s Operation Kitty Caper.”
They crept down alleyways, stopping every now and then to toss bits of dried fish and rice into bowls they’d stashed behind garbage bins.
Daichi squealed with joy when the first cat appeared—a skinny orange tabby that rubbed up against his leg.
“She likes me!” he whispered, crouching carefully to pet her.
“She knows a good soul when she sees one,” Dazai said, almost too softly.
The child giggled as more cats appeared, circling them like royalty. Dazai sat cross-legged beside Daichi, lazily watching as the kid giggled and whispered names for each cat: “Sir Whiskers,” “Detective Meow,” “Fish Breath.”
“I think I like this mission,” Daichi said.
“Of course you do,” Dazai replied. “You’re my best partner.”
Daichi paused, then beamed.
For a moment, everything was still. The city faded behind them. There were no agencies, no suicide jokes, no haunted pasts—just a man with a coat too long and a boy with a bucket hat feeding strays behind a ramen shop.
Dazai stood eventually, brushing himself off. “Come on. Before Kunikida finds out and turns into a full-blown Godzilla.”
“Too late.”
They turned slowly to see Kunikida standing at the alley’s entrance, notebook in hand, veins visible in his forehead.
Dazai gasped. “He’s evolved.”
Daichi tugged Dazai’s sleeve. “Run?”
“Run.”
And they bolted.
The sky outside the Agency had started to shift to orange and gold. Daichi sat on the floor with Kenji, building a tower of rice balls (and occasionally taking bites out of them). Dazai leaned against the window, pretending to nap but quietly watching.
He knew this couldn’t last forever.
A knock came at the door.
Atsushi answered it, then stiffened. “Uh… Dazai-san?”
Dazai’s eyes opened, already knowing.
In the doorway stood Mr. Yamada—neatly dressed in a black coat, eyes tired but apologetic. His hands were folded in front of him, and for once, his voice wasn’t rushed.
“I’m here for my son.”
Before anyone could react, a very specific pen snapped in half.
“You have got to be kidding me,” Kunikida muttered from across the room, standing up. “You vanish for days, dump your kid on us without warning, and now you just waltz back in?”
Yamada shifted awkwardly under Kunikida’s stare. “I—I had work emergencies. I didn't have a choice.”
Kunikida’s glasses flashed. “You had a choice not to leave him in the hands of strangers!”
Dazai raised a hand lazily. “Technically, he left him with you, Kunikida.”
Kunikida glared. “Don’t help me.”
Yamada bowed deeply. “I’m truly sorry. I’ve arranged everything now. I can take proper care of him again.”
The rice ball tower toppled. Daichi turned.
“…Papa?”
Yamada stepped in slowly, kneeling. “I’m sorry it took me this long. But I’m here now.”
Daichi hesitated. The room was suddenly too quiet. His small hand reached instinctively toward Dazai’s coat before he caught himself.
Dazai gave a soft smile. “Go on, partner. Case closed.”
Daichi ran to his father’s arms.
Yamada hugged him tightly, then looked up at Dazai. “Thank you… I heard from the others how much you did for him. I… wasn’t expecting that.”
Dazai shrugged, hands in pockets. “I was bored.”
Kunikida crossed his arms. “Next time you’re bored, try paperwork.”
Daichi turned back one more time, running to Dazai.
“You’ll visit?” he asked.
Dazai crouched, ruffling his hair. “Of course. Who else would solve mysteries with me?”
“Promise?”
Dazai hesitated. Promises weren’t really his thing. But this one… felt different.
“I promise.”
Daichi hugged him tightly. And for the briefest moment, Dazai hugged back.
Then they were gone.
The office was quiet again.
Kenji sniffled. “I miss him already.”
Yosano gave Dazai a long, quiet look.
He didn't say anything. He just returned to his chair by the window, coat wrapped around him, watching the sun go down—pretending he wasn’t waiting for a knock that wouldn’t come.
₊˚⊹ ᰔ