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Jealous

Summary:

The last day of DazAtsu Week 2025 - Jealous

 

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ADA is out and about in an amusement park. Dazai and Atsushi treat it as a date, kind of. The ADA FINALLY figures out that Atsushi and Dazai are dating because of one tiny jealous act.

Also, someone should get Yosano a bucket.

Notes:

Welcome to the last day of DazAtsu Week 2025!

I have tried my best with the fic, I really did but somehow it went away with me.
I am sure you guys will like it anyways, I hope you do. If not, urhm OH LOOK! THERE'S A WALL!

runs away never to be seen again

(See the end of the work for more notes.)

Work Text:

Yokohama, Cosmo World

The whole Agency had decided to have a whole weekend off and make it a trip to Cosmo World. No, it had nothing to do with Dazai threatening anyone with certain death about the last few days strangeness. Whatever gave you that idea? He didn’t threaten Yosano, Ranpo and Kunikida in agreeing to go to Cosmo World because of their grand idea of setting Atsushi up with blind dates. Perish the very thought.

Fukuzawa had just raised an eyebrow when he had been ambushed by the idea, especially because Kunikida was the one to ‘suggest’ the trip to him. ‘Suggest’ right, the man knew what was up with that suggestion but kept his words to himself. He found it a bit funny, if you were to ask him.

Kyōka and Kenji had been all for it, sparkling and rattling ideas off which rides they would go on and what to eat there. Atsushi had gone with the flow while Dazai had stood beside the white-haired boy and seemed very smug. Naomi was all for it because a date with her Jun’ichirō, no need to go further with that. Trust me, it is best we leave it as it is.

“They’re late!” Kunikida hissed, for once not dressed in his usual dress pants, a button up, vest and his ribbon. He wore jeans and a comfortable looking sweater. “We agreed to be here at nine sharp-!”

“Oh hush you,” Yosano sounded amused, hip checking the man. “Relax, will you? It’s just a few minutes!”

Kunikida glowered at her while the woman just smiled. Yosano was wearing a dress, the top started off with a light pink and went darker the further the color went down until it was a blood red. The sleeves reached to her elbows and she wore some heels with them. Ranpo was next to her and sulking, without his usual sherlock getup. He had been forced into shorts and a t-shirt; he was also carrying Yosano’s purse.

“I don’t like this,” the man sulked, Kenji and Kyōka laughing at him. “I have been forced into this!”

Kenji in his usual get up was forced to wear sneakers, the sunshine boy wasn’t minding it. Instead, he had marveled at the colorful shoes while Kyōka had threaten anyone with her knife should they force her to change out of her kimono. Fukuzawa had sighed, not that the man was dressed any differently either. Naomi had exchanged her school uniform for a pink blouse and white skirt while Tanizaki wore jeans and a hoodie instead of his usual sweater.

“It’s only for today, Ranpo-san,” Jun’ichirō tried to sooth. “I am sure that Yosano-sensei will carry her purse herself soon-!”

“That’s not it,” Ranpo huffed annoyed, glaring at the ginger. “I hate these clothes-!”

“Oh, grow up, will ya?” Yosano slapped him lightly. “It won’t kill you to wear something relaxing for once in your life.”

“It will-!”

The two began to bicker and Fukuzawa rubbed at his temples. `I shouldn’t have agreed to this,´ the man could feel a headache incoming already and they had yet to enter the park.

“Ah~! Did you wait long~?” came the sudden call from Dazai, the man appearing at a leisure pace. “I had to make sure my Atsu-chan looks presentable for his first time at an amusement park~!”

Gone was the trench coat, sand colored pants, button up and black vest. Instead, Dazai had on a striped sweater in blue and white, bandages peeking out of the collar and sleeve holes, his palms halfway covered in them. Yosano let out a whistle when she saw the black jeans and shoes the man wore. Naomi tried to look behind Dazai, having notice someone fidgeting behind the man’s frame. `Where is Atsushi-kun? Didn’t Dazai-san say something about making him presentable?´

“Showing off, eh?” the woman had Ranpo in a headlock who tried to bite at her. “Behave, you gremlin!”

“Make me-!”

“Ah, I always good look wherever I go~!” the man sang, pulling someone from behind his frame. “I had to match, ya know?”

“What do you-?” Kunikida was about to ask only to have his jaw drop.

“Kunikida-san?” Kyōka asked, having talked with Kenji when she noticed the shocked look on the man’s face. “What is the matter-?”

Kyōka felt her eyes widen when Dazai pulled Atsushi in front of him. The boy was red in the face and fidgeting in place. `Atsu-nii…?´ Kenji was just as shocked while Ranpo and Yosano sputtered.

“Atsushi-kun/Brat/Atsu-nii!?”

“Y- Yes?”

Atsushi was wearing a skirt light blue in color, reaching to his ankles and white flats on his feet. He wore a long-sleeved blouse, tucked into his skirt, that was white in color. His fringe was pinned back by a flower pin and his cheeks a bright red with all eyes on him. Dazai was grinning smugly and wrapping an arm around Atsushi’s waist, pulling the boy back into his chest.

“I did good, didn’t I?” the man sounded smug.

No one answered him, still too shocked by the sight of Atsushi and how well the boy could clean up. Well, all but one person that is. Fukuzawa sighed and shook his head, walking up to the two.


“Dazai, I had feared you would take longer than ten minutes to show up,” the man told him, nodding at Atsushi who greeting him with a whispered ‘hello’. “I do wonder… What brough this on, though?”

Dazai tried his best to look innocent, Fukuzawa wasn’t buying it. He knew Dazai a bit too well for that by now, `I knew there was a reason for this trip…´

“I wanted to show off my darling Atsu-chan~! There is nothing wrong with that, is there?” Dazai smiled, holding Atsushi a bit tighter who didn’t seem to mind. “It is such a lovely day, isn’t it?”

“Is that so?” Fukuzawa crossed his arms. “It has nothing to do with the blind dates the others tried to set Atsushi up with, hm?”

“I have no idea what you mean, President!” cue wide smile.

“Of course,” Fukuzawa sounded a tiny bit amused. “You do know you could have cleared that up, right?”

“They started it!” Dazai pouted, Atsushi patting him on the hand lightly. “Why did they even do that in the first place? They didn’t say anything about me dating Atsu-chan in the first place.”

Fukuzawa coughed at that, trying to fight a smile, “Why, indeed.”

Fukuzawa glanced behind himself, his employees were still in shock and didn’t seem to have heard them. `Good, I think it is still very hilarious that they haven’t noticed it… Atsushi and Dazai aren’t even subtle about their relationship,´ Fukuzawa had found it very hilarious when he noticed that no one knew that Dazai and Atsushi were dating. What had made it even better? It was the fact that Atsushi and Dazai assumed that everyone knew!

So far, Fukuzawa was the only one that knew about it and that was only by chance. He had walked in on the two kissing, purely on accident!, when he had forgotten something at the office. Atsushi had been a blushing mess and not been able to meet his eyes for weeks after that. Dazai had been more blasé about it. Fukuzawa had congratulated them after telling them to not let this relationship make them blow off their work. He had looked at Dazai for that one, the man had only smiled in answer.

The man had also witness the weird blind dates Yosano, Ranpo and Kunikida had tried to set Atsushi up with. He had promised to himself that he would step in if the three went too far but Dazai had seemed able to handle that. `Well, until that woman,´ Fukuzawa had only heard about it from Kunikida, having not been in the office that day. Thankfully, the blind dates had stopped and Atsushi was none the wiser about it.

Clapping his hands, Fukuzawa watched as the others jumped and blinked at him. They were still processing the sight of Atsushi dressed as he was.

“Shall we head in?” Fukuzawa held the tickets up, having purchased them earlier.

 

A short while later

Dazai and Atsushi were leading the group while Fukuzawa was walking behind them. Kenji and Kyōka had already vanished when they had seen the first food stall. Kunikida had volunteered to look after two, the man wasn’t that keen on riding anything in the park. He had a weak stomach alright? It was already bad enough that he got sick when he was just in the passenger seat when someone else drove. It should also be noted that it was usually Dazai that drove the car then, who knows?

Ranpo and Yosano were muttering to each, watching Dazai hold Atsushi’s hand and pulling the boy closer to his body. `Okay, okay… Let’s be logical about this…´

“Oh~! What about this, Atsu-chan?” Dazai asked, pointing to a rollercoaster with many loops. “Let’s try this one, hm?”

Atsushi turned to look at it, “If I puke, I will puke on you!”

Dazai laughed the threat off, dragging the boy with him and Ranpo watched them. `’Atsu-chan’? Since when does he call Atsushi-kun that? Why are they so familiar with each other?´ Ranpo knew that it could be because of their mentee-mentor relationship but he doubted that. A lot of things weren’t adding up to that, `The blind dates… The clinginess… What am I missing…?´

Keeping an eye on the two, Ranpo decided to follow after them. It wasn’t like he had anything to lose while Yosano begged off. The woman liked some rides but one with so many loops? That wasn’t for her. Naomi had dragged Jun’ichirō off to a mirror house, a cackled leaving her lips.

“Children…” Fukuzawa felt old when he watched them go.

Standing in line, Ranpo yawned when he heard screams while Dazai seemed to vibrate in place. He watched as Atsushi poked the man and Dazai wrapped his arms around the other. He noticed how Dazai settled his hands on Atsushi’s hips again, `Intimate? Why?´ His mind began to race when he saw Atsushi hold one of Dazai’s hands, fingers playing with the other’s. `Atsushi-kun isn’t blushing… He looks relaxed, like he is used to doing this.´

The line was moving quickly, it hadn’t been a really long one either. The Park had just opened a few minutes ago. In a matter of minutes, Ranpo found himself in a cart, next to girl who was clutching the safety bar tightly. There was an excited expression on her face and he yawned. He was already bored. He was more focused on how Atsushi was holding Dazai’s hand, the man whispering to the boy, `Pretty sure stating random facts on how he could die on this ride…´

Yawning again, there was a sound and then the carts lurched and began to move. Keeping Dazai and Atsushi in his sight, Ranpo ignored the squeal from next to him.

“This is going to be a long ride, isn’t it?” he muttered to himself when the girl squealed again and they hadn’t even ascended the peak yet.

 

A few rides later

Atsushi was giggling as Dazai tried to walk in a straight line. It wasn’t like Atsushi was fairing any better either. They had been on a ride with a lot of spins and it was a challenge alone to walk off of the ride. Ranpo was snacking on some cotton candy while Yosano looked green in the face. The woman had gone with them and was now regretting it. Fukuzawa was calmly sipping his tea when they heard a loud shout. It sounded suspiciously like Kunikida.

“Huh, I wonder where the kids and Kunikida are,” Ranpo mumbled through a mouthful, ignoring the scolding look from Fukuzawa. “Meh… can’t be fairing any worse than Dazai and Atsushi-kun.”

“I have so many regrets,” Yosano groaned, heaving heavily. “Why did I go with those two…?”

No one answered her. Atsushi and Dazai had meanwhile managed it to walk over to Fukuzawa and Ranpo, their gait a bit steadier than before. They plopped down on a bench, Dazai leaning back with Atsushi settling into his side.

“Ah, I could eat now,” Atsushi muttered, making Yosano actually puke.

“I don’t think that Yosano-sensei agrees with you on that, Atsu-chan,” Dazai snorted, ignoring the finger that Yosano gave him. “I’m pretty sure her breakfast is going through her head again.”

“That’s not funny!”

“It is to me~!”

After Yosano had emptied her stomach and a scolding from Atsushi, the group made their way over to a food stall. Fukuzawa and Dazai had offered to get the food, Atsushi had given the latter a look when he had tried to sneak off, while the others looked for a table and bench to sit and eat at. Ranpo had the perfect one, with an umbrella and where Kunikida, pale in the face, together with Kenji and Kyōka already sat at.

“Fancy seeing you, Kunikida,” Ranpo greeted, sitting down next to the man and Yosano taking the other side. “You look a bit green there!”

“Don’t remind me,” the man groaned, a water bottle clutched tight in his hands. “Those kids are evil!”

Said kids gave wide grins before standing up, “We’re going to get ice-cream!”

Atsushi, having followed slowly behind them, found himself cornered by a boy and his friends, four in total. Blinking at them, Atsushi tilted his head to the side and tried to suppress a shudder when one smiled at him. It was supposed to be charming but it looked a bit off.

“Ah, can I help you?” the boy tried.

“I am sure you can,” one of them said, stepping closer.

Atsushi took one step back and narrowed his eyes, “Uhuhu, you don’t need to come any closer…”

The boys snickered at their friend when he let out a noise, “Shut up, you idiots!”

Rolling his eyes, Atsushi tried to pass them by. He wouldn’t get involved with whatever this was supposed to be. He had already weird days behind him, thank you very much. His boyfriend had been especially clingy, not that Atsushi minded that, but something had been off about it. He had tried asking Dazai about it but the man had only grunted and refused to let go off him.

“Hey, where are you going?” the first boy asked, black eyes looking right at Atsushi. “I am not done yet with you.”

“I am with you,” Atsushi deadpanned, “I don’t even want to be here, if you excuse me-!”

“Not so fast!” Atsushi yelped when a hand went for his arm, gripping tight.

“Let go-! What gives you the right to-!” Atsushi huffed, trying to tug his arm free.

The grip just got tighter before the boy let go. He had to, one of his friends smacked him in the back of the head, hard.

“Hey, you don’t do shit like that,” the boy was blond.

“Fuck-! Man-!”

The two glared at each other while another, this one with blue hair, stepped up. Atsushi eyed him warily but the other gave him a grin. He relaxed a little, `I hope he doesn’t do something stupid-!´

“So…” he coughed, “we actually wanted to ask you about the woman with you…”

“Woman?” Atsushi blinked, confused when the last boy elbowed the blue haired one. “Huh?”

“Yea, the one in the pink and red dress-!” blue hair coughed, a flush to his cheeks.

“What the doofus here is trying to say, is she single?”

“HA!?”

 

Meanwhile

Dazai and Fukuzawa had come back with the food. Dazai frowning when he didn’t see Atsushi anywhere and looked around. Ranpo was watching Dazai again, still trying to piece everything together. The picture wasn’t forming in his mind yet.

“Where’s Atsu-chan?” Dazai asked, having put the food down on the table while Ranpo went for the fries. “Hey, leave some for Atsu-chan!”

“I still want to know why you are calling him ‘Atsu-chan’,” muttered Yosano, sipping on some tea. “That’s new.”

“It’s not,” Dazai told her, eyes sweeping around before they finally settled on Atsushi. “Aha!”

“It totally is-! Hey, I am not done yet-!” Yosano huffed, only to regret it when the tea nearly came back up. “Oh fuck-!”

Dazai ignored Yosano, more focused on Atsushi and those boys. He didn’t like what he was seeing, he saw red when one of the boys went and gripped his boyfriend like that. He narrowed his eyes and growled, only to blink when one of the boys smacked the other. Huh, what was that about? Before he could think any more about that, the blue haired one stepped up and spoke with his Atsushi.

`Wait-! Is he blushing?!´ Dazai growled lowly, his hands clenching into fists. `You’re dead, no one flirts with my Atsu-chan-!´

“What’s with the look dark, Dazai, huh?” Yosano asked, her nausea having settled a little.

“Plotting murder,” he answered her honestly, eyes dark.

“What-?” turning his head, Yosano blinked when she saw Atsushi surrounding by boys with one, or was it two?, blushing. “Huh, our Atsushi-kun sure is popular, eh?”

“Not if I have anything to say about that,” grumbled Dazai and went to leave.

“Hey, Dazai, you can’t just-!” Yosano hurried to get up only to regret it when she felt her tea coming up again, well nearly that is. “Ugrh, fuck me-!”

She could only watch helplessly as the man went over to Atsushi while holding a hand before her mouth. She kicked at Ranpo when he snickered while Kunikida shot her a look. Fukuzawa sighed and prayed that Dazai wouldn’t go over the top, `I guess he still is not over those blind dates…´ He had seen that Atsushi was cornered by some boys but he knew that the boy could look after himself.

Atsushi would have called for help by now if he couldn’t.

 

Back with Atsushi

“Atsu-chan!” Dazai called out, his voice light, “there you are~!”

“I haven’t left my place, Osamu,” Atsushi rolled his eyes.

The boys watched as a tall brunet went for Atsushi, a shiver going up their spines. It wasn’t helping matters that the brunet glared at them, a glint to his red eyes. `Those aren’t normal eyes,´ the foursome thought, taking a step back.

“Atsu-chan,” the man hugged Atsushi, pulling him closer and leaned their faces close, “if I didn’t know it any better, I’d say you-!”

“Don’t even start,” cue another eyeroll.

The man hummed, glancing to the side and smirking when the four stayed frozen. His gaze was promising them death, a painful one at that. Atsushi sighed and poked at Dazai.

“Oh, stop that,” another poke which went ignored by Dazai, a possessive arm slinging around his waist. “Osamu-! Stop being weird.”

“I am not being weird,” he muttered, turning to give Atsushi a kiss on his cheek. “Just staking my claim before any idiots get ideas.”

“Osamu,” Atsushi sighed, a light blush to his cheeks. “You don’t have to worry about anything, really.”

“Don’t I?” Dazai looked at the four boys who were still frozen. “What about them, then huh?”

Atsushi sighed before giving Dazai a quick peck on the lips, “They just wanted to ask me about Yosano-san, not everyone wants to flirt with me, you doofus! So, stop this jealous act, will you?”

“WHAT THE FUCK-!”

“SINCE WHEN-!”

“I FUCKING KNEW IT! SOMETHING WAS FISHY ABOUT THIS ALL- URGH!”

“SOMEONE GET A BUCKET FOR YOSANO-SAN!” that was Kenji.

Atsushi and Dazai jumped at the loud yells while the four boys had turned to look where the yelling had come from. Yosano was hurling into a bucket with Ranpo holding her hair back. The detective had his eyes wide open and was looking at Dazai and Atsushi with shocked eyes. Kunikida had fallen from the bench while Kyōka looked like she had a revelation. Kenji was waving at them, the only happy one.

Fukuzawa was seen shaking his head and acting like he didn’t know any of them. He was doing a real good job of it also, especially with so many eyes trained on them all and him sitting at the same tables as the others.

“What in the-?” Dazai and Atsushi stared at their friends, lost as to what made them react like that.

The four boys were forgotten and they took that as their chance to escape. As nice as Atsushi had been, his boyfriend was terrifying, alright? They had only been around the man for a few minutes but his aura screamed killer when he glared at them. `One jealous bastard,´ they all thought while fleeing.

Maybe they would have to approach this Yosano-san when neither Atsushi nor his boyfriend was around. They didn’t fancy being killed for looking at Atsushi too long. They hadn’t even wanted anything from him.

“YOU TWO! GET YOUR ASSES OVER HERE! YOU OWE US AN EXPLANATION!” Kyōka screamed, a few things made sense to her suddenly. “ATSU-NII! DON’T TELL ME YOU-! NOT DAZAI-SAN-! ANYONE BUT HIM!”

“Ha?” Atsushi and Dazai looked confused at each other.

What the hell was that about?

 

A short while later

After a lot of yelling, Fukuzawa still acting like he didn’t know any of them, Dazai and Atsushi were finally allowed to speak. The two had been confused at Kyōka and Ranpo ranting at them. Kenji had just smiled and poked at Yosano who was weakly glaring at them all. The woman was still a bit green in the face and that one time she had tried to speak. Well, the basket was her best friend right now.

Kunikida had been the only one silent, an absentminded look about him. His eyes had glazed over a little, like he was remembering the last few weeks.

“Atsu-nii, how could you keep it from me that you are dating that walking waste basket?” Kyōka asked, finally having run out of steam and staring at her big brother. “I thought you had taste…”

“Ah? I thought you knew,” Atsushi answered her, his answer sounded more like a statement. “It’s not like Osamu nor I were hiding it… I figured you and the others accepted us when you didn’t say anything about us dating.”

“What do you mean you thought we knew?” Ranpo asked, his head pounding. “A lot of things make now more sense…”

“Like Atsu-chan said,” Dazai shrugged, wrapping an arm around Atsushi and pulling him into his side, “you guys are normally so noisy and nothing escapes your notice, now does it, Ranpo-san? You are also the first to gossip with Yosano-sensei.”

Atsushi nodded at that, “Uhuhu! So, we thought there was no need to tell any of you because you would do it for us… Like you always do.”

“Hey-! You make it sound like I don’t know when to keep my mouth shut,” Ranpo grumbled, rubbing at his temple.

“Because you don’t,” Fukuzawa threw in, giving him a meaningful look. “You never do, so I am with those two… Then again, I found it hilarious how you didn’t notice the obvious.”

“President-!” came the offended gasp.

“For being so smart, you sure can be stupid, Ranpo-san,” Dazai snickered, only to get an elbow from Atsushi in the side. “Rude, Atsu-chan!”

“Be nice,” a scolding look which had Dazai pouting.

“If that waste of good medical supplies hadn’t acted on his jealousy right now,” Kunikida finally spoke, looking at the two in a new light. “… Would we ever have realized that you two are dating?”

There was a silence, no one having an answer to that. Kyōka was still trying to accept the fact that her brother was dating Dazai of all people. Kenji had already lost interest in the topic; city people sure like to be hung-up on such stuff. He was happy that Atsushi and Dazai had found happiness with each other, even if he hadn’t known about it at first. Why bother to keep talking about it when it was already said and done?

“I’d say you would still be clueless, even if those two moved in and married,” Fukuzawa offered, lips twitching at sour looks that earned him those words. “We have to be real here.”

“… I had been wondering why more and more stuff yours went missing, Atsu-nii,” Kyōka muttered, shooting Dazai a nasty look. “It makes so much sense now… The nights you were gone… The silly smiles… Oh my god-! How didn’t I see it!? We’re living together-!”

“Ah, Kyōka-chan, don’t be too hard on yourself-!”

“I don’t think you can help her with that, Atsu-chan,” Dazai was watching as the girl began to pull at her pigtails. “Give her a bit… I am sure she will try to murder me soon enough.”

“Don’t joke about that-!”

“… Fucking Ed-kun! He knew!” Ranpo suddenly exclaimed, groaning loudly. “He knew and he even told me-! I am so stupid-! HOW CAN I CALL MYSELF THE GREATEST DETECTIVE-!?”

Atsushi and Dazai could only watch on as their friends and colleagues began to mutter to each other again. Yosano was also taking part in it now, having emptied everything in her stomach and looking a bit better.

“Those dates-! Fuck, of course, Dazai would go after Atsushi-kun,” Yosano groaned, running a hand through her hair. “We should have known then-! How can we be so blind?”

“… Wanna go on another ride, Atsu-chan? This is getting too gloomy for me,” Dazai asked, nudging the boy to get up.

“… Shouldn’t we stay and-?”

“Eh, they’re having a crisis… Let us have some fun before they get their bearings back and grill us,” Dazai was already up and pulling Atsushi with him. “I should have known it was too easy of them accepting us dating like that… Oh well~!”

“Osamu-!”

Notes:

I have no idea what happened here but I am sure this went away on me.
Eh, well... whatever!

That's the end of the week and I hope you enjoyed it. I ended it where I did because this would have gone in cirlces otherwise.
I can tell you this though, Dazai and Atsushi got grilled on how they started dating later on. Ranpo and the others still beat themselves up for not noticing.

As for Naomi and Tanizaki... They only found out a few weeks later when DazAtsu kissed in the office because reasons.

To think, that my week hasn't arleady been enough with my account stolen and now disabled. No, my toothache is still there. There is something even worse, one of our dogs got chased by another dog and now we have a problem. She was bitten and can't walk anymore... We worry for her and we are angry with the idiot that couldn't control his damn dog! My parents will report him and have him pay for the vet, that much I know already. Tension is thick here...

I HOPE YOU LOT HAD A BETTER WEEKEND THAN I DID!

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