pairing- Nagumo Yoichi x reader
summary: you are Takamura’s granddaughter, a well-trained assassin who never got the chance to shine. That was until one day, when The Order observed your skills and offered you a position in the association.
All new colleagues seemed happy, everyone but him. His dark coat, eyes, and hair all indicated how much he loved hiding. And how much he loved hating you, the opposite of him, who he considered had no right to be there—also, the one who hates how you make his heart skip a beat.
tags & warnings-> reader is 19, Nagumo is 27, age gap one-shot, office au, forbidden love, enemies to lovers, playboy x sweetheart, angst and smut, Takamura is still everyone’s nightmare except Nagumo’s, mentions of blood, reader has awfully little experience, also there might be some Shishiba x reader here and there
status: ongoing
CHAPTER ONE
Your heels echoed sharply against the polished marble floor as you hurried through the halls of JAA headquarters, heart pounding like a war drum beneath your ribs. Today was your first mission assignment—finally—and you couldn’t afford to be late. Until now, your days had been consumed by endless stacks of paperwork and the suffocating monotony of office life. You had spent months trapped behind a desk, watching your colleagues vanish into the field with adrenaline in their veins and dirt on their boots, while you were left to file reports and refill pens.
Worse than the boredom? Him. Mr. Teaser himself. Nagumo Yoichi.
He had a knack for appearing unannounced, like a storm you forgot to check the weather for. He’d swagger into your office, track blood onto the floor, and drop off yet more work with a smirk that made your skin crawl. Then he'd lean against your desk like he owned the building, casually recounting his latest mission while enjoying the fact that you weren’t going anywhere but the copy machine.
Nagumo Yoichi was infuriating. Arrogant, smug, and endlessly teasing. Your sworn enemy in the office.
You had complained to your grandfather once—just once—about him. The next morning, the office was in chaos. Nobody could prove it, but you were fairly certain he had orchestrated the blackout and the internal security breach just to send a message. Since then, you’d tried locking Nagumo out of your workspace, but he always found a new way to slink in. Like a cockroach in designer clothes.
“You know my gram—Mr. Takamura—would murder you if he knew you were sneaking around like this,” you’d warned him once, half-joking.
He just grinned and said, “Worth it.”
Today was your moment. Your shot to prove that you were more than just a glorified secretary. That you belonged out there in the field, not behind a desk with Nagumo leaning over your shoulder and driving you insane.
You didn’t realize how deep in thought you were until Oki’s office door appeared in front of you like a boss battle checkpoint. Damn it—had you just spent the whole walk thinking about him again?
You shook the thought away and knocked, forcing yourself to stand tall. A calm voice answered from the other side.
You slid the door open, stepping inside with a respectful bow and closing it quietly behind you. Oki’s office was lined with towering bookshelves, each one filled with neatly arranged volumes on strategy, history, and intelligence operations. It smelled of old paper and cedarwood—a scholar’s haven, not a battlefield. Yet somehow, the air felt heavier than usual.
"Miss Y/N," Oki greeted you warmly. "Thank you for coming on such short notice. I wasn’t sure you’d accept the assignment, especially considering it’s your first infiltration mission. I assumed you’d prefer more training first.”
“I’m honored, Mr. Oki, truly.” You clasped your hands behind your back. “I want to prove that I can do more than just paperwork.”
He smiled, but there was hesitation in his eyes. “Of course. You’re his granddaughter, after all. I’ve seen your combat potential... but your grandfather was always there to back you up. This job is different. Are you sure you’ll be fine on your own?”
In translation: Don’t screw this up.
“Yes, sir.” Your voice didn’t waver.
“Good.” He leaned back slightly. “But just to be safe, I’m assigning you a partner. I know the two of you don’t exactly see eye to eye, but consider it a learning experience.”
Your heart skipped a beat.
A low voice spoke from the window behind Oki’s desk. “What could I possibly learn from her?”
You didn’t need to turn around. You knew that voice.
And there he was. Perched casually on the windowsill like some noir-era devil, a pocky stick lazily hanging from his lips. One hand was in his tailored black suit pocket, the first two buttons of his white shirt undone just enough to hint at trouble. His dark hair was swept back in deliberate chaos, and there were smears of blood on his sleeve—a souvenir from whatever mess he’d just crawled out of.
Nagumo Yoichi. Walking distraction. Living migraine. Immune to boundaries and personal space.
You crossed your arms. “Mr. Oki is going to strangle you one day if you keep doing this.”
He shrugged, completely unbothered. “What can I say? You’re fun to bother.”
“Respecting your higher-ups, for example,” Oki interrupted, rubbing his temples. “Nagumo, I’ve told you a million times: stop breaking in through the window. Use the door like a normal person.”
Nagumo tilted his head and smirked. “And you thought I was normal?”
Oki sighed in defeat. “That’s on me.”
As the two men volleyed passive-aggressive jabs, you drifted toward the bookshelves, running your fingers along the spines. It was a habit by now—one of the few things that brought you comfort in high-pressure rooms like this.
You snapped out of it. “Apologies, Mr. Oki.”
“No harm done. I’m just glad someone around here appreciates history.” He threw a pointed look at Nagumo.
Nagumo rolled his eyes dramatically. “What’s the point? They’re all dead anyway.”
You watched the corner of Oki’s eye twitch.
“Why did I ever think pairing you two would be a good idea…” he muttered. “Miss Y/N, if you'd prefer, I can reassign your partner.”
“No, sir!” You straightened, hands clenched at your sides. “Please, don’t worry. I’ll manage.”
Oki gave a slow nod and stood, walking over to his desk. He handed you a sleek black folder, the kind used for high-level intel. Inside: Everything you need to know. Targets. Layouts. Dates. Backstories.
“What’s the job?” Nagumo drawled, suddenly behind your left shoulder.
You didn’t even hear him move. One of his fingers gently brushed the skin behind your ear as he tucked a strand of hair back. You froze.
“Does your dear grandfather know you’ll be out of his sight? With me, of all people?” he whispered, voice low and teasing.
You swatted his hand away, cheeks burning. “Mr. Takamura was thrilled to see me finally take on a mission. Although he is more than prepared to end your life if something happens to me. Understood?”
Nagumo grinned. “Crystal clear, ma’am. I pinky promise to keep you safe~”
“Why do I have a really bad feeling about this?”
“I don’t know… Maybe you’re just paranoid.”
You narrowed your eyes. “How do you not even know what the mission is?”
“I’ve been busy, unlike some people.” He winked. “Had to cancel a meeting with Sakamoto just to be here.”
You opened your mouth to fire back, but Oki clicked his pen—a subtle way of saying cut the crap. You took a step back, flipping open the folder to study the mission details.
And then your heart plummeted.
Two words stared up at you like a slap to the face: husband and wife.
“…Sir?” you croaked, lifting the page and pointing at it like it might spontaneously correct itself.
Oki turned to the window, suddenly interested in the weather.
“No,” he said, voice a little tighter now.
“What the hell is this?” Nagumo snapped, stepping up beside you.
“I’m sorry,” Oki said with a heavy sigh. “But that’s the cover. It’s the best way to get into the gala unnoticed. I’m not changing it. This is Miss Y/N’s mission, and I trust her more with you than with anyone else.”
“No buts. You leave tomorrow morning. This conversation is over.”
You blinked. Then nodded.
This was your chance. You wouldn’t let anyone ruin it. Not even him.
You bowed once more and turned to leave, folder in hand. And, of course, Nagumo followed, trailing behind like the dramatic storm cloud he was.
“I still don’t get it,” he said. “What are we doing?”
You glanced at him over your shoulder. “There’s a gala being held by an IT magnate. He used to be one of our sponsors. Two years ago, he leaked intel to the enemy. That betrayal started the war we just barely won. Now, he’s going to pay.”
You could feel Nagumo go still beside you.
“What? Cat got your tongue?”
“…Are you sure about this?”
You turned to him, arching an eyebrow. “What, scared of pretending to be all lovey-dovey with me?”
“No. I’m scared of your grandfather.”
“We both know that’s not true. What’s the real reason, Nagumo-senpai?”
He rubbed the bridge of his nose, groaning. “Can’t believe I’m taking orders from you…”
You barely heard him. Your eyes were on his hands—long fingers, a faint scar near his knuckle. They were absurdly attractive hands. And that was not a helpful thought.
“I’m just worried you’ll screw up,” he continued. “You’ve never done this before. And you hate me.”
“I’ll be fine,” you snapped, more harshly than you meant. “Thanks for the concern, senpai.”
That was when he spun you around and pinned you to the wall.
You didn’t even see him move. One moment, Nagumo was teasing you as usual. The next, your back hit the wall with a thud, his arm braced beside your head, his body so close you could feel the heat radiating off him. The hallway was dim, empty. Just the two of you. And your heartbeat is hammering in your chest like a war drum.
“What the hell are you doing?” you hissed, breath catching.
His eyes searched yours. Dark, stormy. Not playful this time. Not teasing.
“Just… stop pretending,” he muttered. “You don’t hate me.”
He leaned closer. “You don’t.”
“I do,” you whispered, glaring up at him.
“Then why,” he murmured, his fingers brushing lightly against your wrist, “does your pulse race whenever I touch you?”
You didn’t have a good answer for that.
And that annoyed you more than anything else.
You shoved him back with both hands. “You’re insufferable.”
“Mm. But still pretty, right?” he smirked, letting you go. “That’s gotta count for something.”
“I swear, one of these days, Mr. Takamura is going to kill you, and I will cheer.”
He held up both hands in mock surrender as he backed away. “Noted. I’ll be on my best behavior, sweetheart.”
“Call me that again, and I’m setting you on fire.”
As if summoned by your pure rage, a third voice entered the hallways. Cool, deep, and amused.
“You two done flirting, or should I come back later?”
You turned—and there he was.
Sleek, silent, dangerous. He stepped into the light, adjusting the black gloves on his hands like he’d just finished choking someone out and wanted to keep his sleeves clean. His long coat fluttered behind him, dark eyes unreadable as they flicked between you and Nagumo.
Great. Just what you needed: another assassin with a talent for unnerving silence and dangerous charm.
Nagumo sighed. “Why are you here?”
Shishiba tilted his head. “Oki sent me to deliver your equipment. But honestly… I was curious. Heard you two were playing house. I had to see it for myself.”
You snatched the folder tighter to your chest. “It’s not ‘playing.’ It’s a cover. A mission.”
“Sure,” Shishiba said smoothly. “A cover. That involves sharing a hotel room. And pretending to be madly in love. For several days. Alone.”
Nagumo glared at him. “Don’t you have somewhere better to be?”
“Not really.” Shishiba smirked slightly. “Besides, I’d kill to see you in a tux, holding a champagne flute and pretending not to be emotionally repressed.”
Nagumo looked like he was about to commit a felony.
You stepped between them. “Can you two stop posturing like rival cats in mating season? We have work to do.”
Shishiba chuckled. “She’s already in charge. I like her.”
You pointed a sharp glare at him. “And if I catch either of you making this mission harder than it needs to be, I will file a report.”
Nagumo raised an eyebrow. “You mean like the one I found in your desk drawer last week? Cute handwriting, by the way.”
“You went through my stuff?!”
He grinned, brushing past you like a smug hurricane. “You keep saying that. I think it’s your love language.”
You were going to explode. One day. And when you did, Nagumo Yoichi would be the reason.
That night, you stared at your suitcase, freshly packed, sitting by the door.
Inside were weapons disguised as makeup, encoded USBs, and a red silk dress meant to distract your target.
You weren’t nervous about the mission.
You were nervous about him.
About the way he looked at you sometimes, like you were a puzzle he couldn’t solve.
About the way your stomach twisted when he got too close.
This was your first mission. Your first chance to be more than someone’s shadow. To make a name for yourself outside your grandfather’s legacy. To show the world—and yourself—that you were capable.
But God help you… if Nagumo touched you again like that—
You groaned and threw a pillow at the wall.
“I will end him if he fucks this up.”
Then your phone rang. Wondering who it was, given the fact that it was already past midnight, you got up from bed and went to your desk, sat by the window to check.
“Hey! Sorry for the late hour. I was thinking you would already be sleeping since you have to be at the airport first thing in the morning.”
“Despite that, I just couldn’t close an eye even if I tried.”
There was a pause after your answer, and a soft chuckle could be heard from the other side of the line.
