#seijoh four

[aizofshiguro]

꒰ doing a loyalty test on your bf .ᐟ ꒱

— seijoh four edition :: o. tooru, m. issei, h. takahiro, i. hajime. established relationship. mentions of matsuhana bromance. crack-ish. and then there's timeskip iwa with the assurance.

꒰ o. tooru ꒱

꒰ m. issei ꒱

꒰ h. takahiro ꒱

꒰ i. hajime ꒱

all rights reserved © 2026 AIZOFSHIGURO. ଳ ⋆˚࿔ masterlist :: i miss haikyuu and seijoh sm have some crumbs,, lmk if i should do more of these ^^

[cottonlemonade]

Thinking about how Iwaizumi and Oikawa are entering the gym only to find Mattsun and Makki huddled in a corner. Conspiring.

“What are you two up to now?”, Iwaizumi asks and casually kicks Makki’s foot.

His friend taps the end of his pencil against his lips in thought and replies, without looking up, “Making a list.”

Mattsun, ever so helpful, explains, “We’re weighing the pros and cons of him finally asking out y/n.”

Oikawa grinned and squatted down to see the paper. Clearing his throat he began to read: “Pro - thinks I’m funny, Con - also thinks Issei is funny. Pro - soft like a… like a walking body pillow - really?”

Makki nodded dreamily.

Oikawa sighed and continued, “Con - likes the same pudding flavor I do - how is that a con?”

“Because I’d feel obligated to give her my pudding.” Makki said it as if that should have been obvious.

Iwaizumi groaned in annoyance.

“Pro - actual physical manifestation of my dream girl.”

“You’d think that would be top of the list.”, Iwaizumi grumbled and kicked Makki’s foot again, harder this time.

“Con - too good for me. Hey, come on, Makki-chan. I mean, you’re right, but that shouldn’t discourage you.”, Oikawa said genuinely, which earned him a sad glare from the boys on the floor.

“Pro - small hands.”, he paused in confusion, “What?”

Makki leaned back against the wall of the gym and shrugged, “Her hands are much smaller than mine. Puts things into … perspective.”

Oikawa and Iwaizumi frowned, Mattsun nodded sagely.

[nkogneatho]

you cannot convince me that seijoh four haven't frotted with each other before, brushed it off by saying no homo though and acted completely normal the next day at practice. obviously oikawa proposed the idea to a dick measuring competition before it turned into something so shameless and lustful. iwaizumi had to hold himself back from shooting his load to soon when he saw how flushed and long oikawa's dick is. damn it would look so pretty in his mouth. he glanced and makki and mattsun who were taking it not so casually and full on making out. soon the sound of wet lips smacking against each other and the shlurp schlurp schlurp of the cocks filled the room. and then followed oikawa's whimpers and moan. the way he begged pleasepleaseplease to iwaizumi to make him cum, the way he almost teared up when iwaizumi teased his balls, it caused the rest of the boys' eyes to widen. now the three of them were having a very sinister imagination of fucking oikawa till he's overstimulated and crying.

yeah you would think everything's normal the next day, except all of them really want to fuck each other.

[renardiererin]

10.20 - kinktober day twelve ִ ࣪𖤐 tit sucking , ft. takahiro hanamaki

ever since your spontaneous decision to uproot your life and move cities, you’d been staying in the extra bedroom at your high school best friend mattsun’s apartment. obviously you were familiar with his group of friends, they were all essentially inseparable for four years. you never had any issues with them, in fact, they were always rather friendly towards you. iwaizumi would split half of his sandwich with you if he knew you were hungry, and oikawa helped you get over some of your worst high school breakups. makki, though, was always different. always letting his eyes linger on your ass a little too long when you walked away, and you never would’ve known if not for the time he slipped up and stared without noticing the mirror in front of you, giving you a direct view of his eyes and where they were directed. every day after that you’d swing your hips just so slightly more when you’d walk away, be a bit more dramatic when you’d bend over to pick something up. for years it was nothing but casual, unspoken tension simmering between the two of you: a sudden heat blazing when you’d hold eye contact for a second too long. nobody ever dared comment on it, and neither of you two ever dared act on it. 

when mattsun told you makki was gonna be in town for a few days staying on the couch in your shared apartment, you never could’ve planned on it ending up with you straddled over makki’s lap, his breath fanning across your neck as he trails messy kisses down the side of it. his hands desperately grabbed at the fat of your ass, your hips grinding down on his length to find friction between your legs. 

you let out a whimper at the catch of the fabric of his pants against your clit and he slapped a hand up to cover your mouth. 

“careful, baby. wouldn’t wanna wake up mattsun now would we?” you felt the press of his teeth against your neck as his lips curled into a smile.

mattsun was sleeping in his room less than 30 feet from your current position on the couch… on top of his best friend. “makki…” you sighed against his fingertips, reaching your hands to the waistband of his pants. 

he swatted away your prying fingers. “not yet.” 

his cold hands trailed their way to the hem of your shirt, playfully tapping against your bare skin beneath the loose fabric of your clothes. he slid your shirt up slowly, pulling it over your head. your nipples pebbled at the surge of cool air, and makki shamelessly moaned at the sight of your bare chest. 

he panted, breath hitting your tits, silent for a what felt like a full hour. “what? makki, what? why are you just staring at my tits? fuck, do something,” he cut off your complaints by attaching his mouth to your breast. 

your back arched up into his mouth, hands burying in his hair as his tongue swirled around your nipple. he brought his other hand up to massage the neglected side of your chest, his groans vibrating throughout your whole body. 

he switched sides, pinching and pulling at the nipple of your unsucked breast, flattening his tongue against your sensitive bud. your hips flushed down against his, rocking back and forth against his throbbing dick, whining his name as you chased after your release. 

repetitions of his mumbled, slurred name fell from your lips, your hands tightening in his hair and pressing him closer to your chest. you were grinding on him as if he was inside of you, pressing down against him a final time and throwing your head back before slowing your movements on his lap. “fuck” 

“holy shit did you just cum from me sucking your tits?” 

“yes.” 

“holy shit please never put a shirt on again” makki looked up into your eyes, his pupils blown wide—

— and the door cracked open behind you. “what the fuck are you guys being so loud for? oh my god. oh my GOD, are you serious?? are you dead fucking ass right now??” 

safe to say mattsun never let you live that down. 

taglist

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[ghostlynightpanda]

Im so glad i found your tumblr account! I loved your oisuga fics on ao3, their so cute! Could i ask for a react for seijoh 4 (Oikawa, Iwa, Makki, Mattsun) and how they react when their best friend would admit he has a crush on the sister? so, oikawa tells Iwa he likes his sister and other way and for Mattsun and Makki? I hope you know what i mean, english is not my best language.

Seijoh 4 react to their best friend having a crush on their sister

A/N: Thank you for the request, I had so much fun with this one! Their dynamic is so chaotic in the best way.

content/warnings: Oikawa, Iwaizumi, Matsukawa, Hanamaki, fem!reader, fluff, 2.121 words

Oikawa 

The gym echoed with the rhythmic thuds of volleyballs being spiked and bounced, but the sound that really turned heads was Oikawa Tooru's dramatic gasp, loud enough to rival a Broadway performance.

"You WHAT?!"

Iwaizumi Hajime winced, already regretting every life decision that led him to this moment. "You heard me, Shittykawa."

"No, no, no. I refuse to believe this," Oikawa said, hand dramatically clutched over his heart like he'd just been personally betrayed. "My best friend. My lifelong comrade. The one who's been through every match, injury, and salty post-game milk tea with me… is in love with my sister?!"

"Crush on. I said I have a crush on her," Iwaizumi corrected with a groan, running a hand through his hair. "And I didn't even want to tell you like this. But you kept pressuring me to tell you who I've been texting at night, so here we are."

Oikawa began pacing like a telenovela protagonist, muttering dramatic monologues under his breath. "Of all the girls in the world. The fangirls, the classmates, the admirers… My sister. My precious little sister. How will I face my family again? How will I—"

"She's a year older than you," Iwaizumi deadpanned.

"—How will I face her again?!" Oikawa finished anyway, ignoring the correction.

Iwaizumi sat down on the gym bench, letting Oikawa spiral a little. Better to let the drama burn out naturally. Honestly, this reaction was better than being punched. Which, to be fair, had been a possibility.

After a long sigh, Oikawa stopped pacing and stared at him.

"…So, do you like her for real?"

Iwaizumi looked him in the eye, earnest. "Yeah. She's smart, kind, funny—though just as annoying as you when she wants to be—and she doesn't put up with my crap. We've been talking more, and… yeah. I like her. A lot."

Oikawa squinted. "You're not just doing this to become part of the family and get free Oikawa genetics in your future children, right?"

Iwaizumi threw a towel at his face.

"Okay, okay!" Oikawa laughed, catching it and flopping onto the floor like a fallen star. "Honestly… as much as I want to be mad and pretend I hate this, I can't really think of anyone I'd trust more than you."

Iwaizumi blinked. "Wait, really?"

"Yeah." Oikawa grinned, then wiggled his eyebrows. "But I will be asking invasive questions about your intentions and reminding you that if you break her heart, I will spike a volleyball directly into your soul."

"Fair," Iwaizumi said with a chuckle. "So… we're good?"

Oikawa rolled over dramatically and sighed like a dying hero. "We're good. But I'm watching you, Iwa-chan. Always watching."

"Yeah, yeah." Iwaizumi stood, grabbing a volleyball and tossing it toward Oikawa's head. "Now get up, drama queen. We've got training to finish."

Oikawa caught it effortlessly, a glint in his eye. "I'm only letting you date her if you win against me in a spike-off."

Iwaizumi grinned. "Bring it on."

Iwaizumi 

It was a normal afternoon. Practice had just ended, the sun was starting to dip below the gym windows, and Iwaizumi was toweling off the sweat from his neck when Oikawa dropped a verbal bomb with all the subtlety of a flying volleyball to the face.

"Hey, Iwa-chan," Oikawa said casually, dribbling a ball by the bench. "So, uh… I might be in love with your sister."

Iwaizumi froze.

Completely.

Didn't blink. Didn't breathe. Just stared like he'd seen the ghost of every bad serve Oikawa had ever made.

"…You what?"

Oikawa chuckled, rubbing the back of his neck, that sheepish but somehow annoyingly charming grin spreading across his face. "You heard me."

"Nope," Iwaizumi said quickly, standing up. "Try again. Maybe in a language where that doesn't sound like a terrible idea."

"Iwa-chan, come on—"

"Nope." Iwaizumi paced now, towel forgotten. "Out of all people? My sister? You've got a literal fan club. Girls write you letters, stalk your Instagram, scream when you blink at tournaments. And now you want her? My sister?!"

Oikawa looked genuinely flustered now. "Okay, first of all, I don't ask for any of that—well, not all of it—and second, she's nothing like them."

Iwaizumi glared, but Oikawa wasn't backing down. In fact, he looked… kind of serious. Sincere, even. And that was worse.

"She's not just pretty," Oikawa continued, his voice dropping to something softer. "She's smart, and she doesn't care about the volleyball stuff. She teases me, keeps me grounded. She made me dinner when I sprained my ankle last month and told me to stop being a baby—do you know how nice that felt?"

Iwaizumi's face twitched. "Wait, that's why you were over at my house for three hours?"

"…Partly."

"You little—"

"Iwa-chan, listen." Oikawa stepped closer now, serious for real. "I'd never mess with her. Or hurt her. Or treat this like it's not something big. She's your sister. That means something to me."

Iwaizumi looked at him, eyes narrowed, jaw tense. The silence hung there for a long minute, heavy with every memory they'd shared since they were kids—every match, every late-night practice, every time Oikawa pissed him off but somehow stayed his best friend anyway.

"…I know you wouldn't hurt her," Iwaizumi muttered finally. "That's the problem."

Oikawa blinked. "Huh?"

"You're serious about her. Which means I can't even yell at you properly," Iwaizumi said, clearly annoyed by his own restraint. "But also—if she ends up falling for you, I'm gonna have to deal with watching this face at family dinners."

Oikawa smirked instantly. "This face? You mean this face?" He flashed his brightest, most infuriating model-pose smile.

"Stop it. I'm already regretting this."

"But that means you're not forbidding it?"

"I'm not forbidding it," Iwaizumi said, groaning into his hands. "But you so much as make her cry, and I swear to every volleyball god there is, I'll spike a ball and crush your face."

"I wouldn't expect anything less," Oikawa said with a soft smile.

Iwaizumi sighed. "Just… don't tell me how it's going. I don't need the details."

"But what if she—"

"I mean it, Oikawa."

"…Fair."

Matsukawa

The gym was quiet after practice. The team had already filtered out, the lights slightly dimmed, and the only sounds were the squeaks of shoes and the rustle of sports bags being packed up.

Matsukawa sat on the bench, stretching out his legs with a groan. "My knees are filing for retirement."

"Tell them to take mine with them," Hanamaki muttered, slinging his towel over his shoulders. He sat down beside him, unusually quiet.

Matsukawa gave him a side glance. "You good? You're not usually this serious unless someone takes the last energy drink."

Hanamaki tapped his fingers on his knee. "Okay, so, hypothetically... if one of your teammates were to like your sister... would that be a murder-worthy offense?"

Matsukawa blinked slowly.

"Hypothetically," Hanamaki added quickly, a lazy smirk forming on his lips, but the edge of nervousness behind it wasn't lost on Matsukawa.

"…What."

Hanamaki leaned back like he had all the time in the world. "You heard me."

Matsukawa squinted. "Please tell me you're talking about Kunimi. Or Kyoutani, even. Anyone else."

Hanamaki grinned. "Unfortunately for you, I'm referring to your very real best friend. You know, the one who brought you those onigiri after you failed your last exam. Your sister opened the door, by the way, and completely ruined my life with a smile."

Matsukawa stared at him like he was trying to solve a complex math problem with emotional consequences.

"You're serious," he said slowly.

"As a line judge during match point," Hanamaki said smoothly.

Matsukawa let out a long, suffering sigh and tilted his head back. "You like my sister."

"She's funny. She's cute. She didn't flinch when I made a joke about Oikawa's hair being a national disaster. She's basically perfect."

Matsukawa gave him a flat look. "You're my best friend, Makki."

"I am."

"And you're also a sarcastic menace with a talent for chaos."

"Also true."

"And you like my sister."

Hanamaki looked over at him, this time more serious. "Yeah. I do."

Matsukawa was quiet for a moment, then finally sighed again, rubbing his temples like this was a long time coming. "Okay. Okay. I'm not gonna punch you."

"Generous."

"But if you mess this up, I will replace all your shampoo with glue, salt your lunch, and tell Oikawa your deepest secrets."

Hanamaki's eyebrows rose. "You know my deepest secrets?"

"I will find them, Takahiro."

Hanamaki laughed, and Matsukawa rolled his eyes, but the corner of his mouth twitched upward.

"Honestly," Matsukawa added, leaning back, "she could do worse. But I swear, if I hear you used a pickup line that started with 'are you a libero—'"

"—because I'd fall for you anyway?" Hanamaki finished with a wink.

"I hate you so much," Matsukawa muttered, but he was smiling now.

"I'll be good to her," Hanamaki said after a moment, quieter this time. "You know that, right?"

Matsukawa glanced at him, and his usual lazy grin softened into something more sincere. "Yeah. I know."

There was a pause.

Then Matsukawa said, "But just to be safe, I'm still watching you."

Hanamaki stretched and stood up, slinging his bag over his shoulder. "Of course you are. That's what brothers do."

Hanamaki

The walk home after practice was usually filled with nonsense — fake arguments over who forgot to refill the water bottles, dragging Oikawa's fashion choices, maybe one or two existential crises about school.

But today, Matsukawa was quiet.

Too quiet.

Hanamaki noticed around the third block. "Alright. Spill it."

Matsukawa blinked. "What?"

"You've been sighing like you're in a high school drama. Which, fair, I guess — we are in high school — but still. What's up?"

Matsukawa scratched the back of his neck. "Okay, but you have to promise not to get weird about it."

Hanamaki narrowed his eyes. "Whenever someone says that, it's definitely going to be weird."

"Probably," Matsukawa muttered. "But... I like someone."

"Ohhh," Hanamaki said, like the conversation just got more interesting. "Who's the lucky person? Is it that girl from class 4 with the cool nails?"

"Nope."

"…Not that upperclassman from the library?"

"Nope."

"…Wait—" Hanamaki stopped walking, expression suddenly wary. "You're not about to say Oikawa, are you? Because I'll support you, but I need time to emotionally prepare for that."

Matsukawa actually laughed. "God, no. Definitely not Oikawa."

"Then who?" Hanamaki asked, still not moving.

Matsukawa looked at him. Hesitated. Then went for it.

"…Your sister."

Silence.

Hanamaki blinked.

"…Wait. My sister?"

"Yeah."

"My actual sister?"

"Unless you've got a secret twin I don't know about, then yeah."

Hanamaki's expression went through about five emotions in five seconds — surprise, disbelief, slight concern, and finally: "You're kidding."

"I'm not."

Hanamaki squinted like Matsukawa had just told him he wanted to date a ghost. "Why? When? How?"

Matsukawa shrugged, trying to play it cool, but the pink creeping up his ears gave him away. "She's just… funny. And smart. And she's cool. I started liking her a while ago. It just kind of… happened."

Hanamaki narrowed his eyes, hands in his pockets. "You realize this is the part where I'm supposed to threaten your life, right?"

"I figured."

"I'm still thinking about it."

Matsukawa held up his hands. "Look, I get it. If you're not cool with it, I'll back off. I'm not gonna risk our friendship for this."

Hanamaki was quiet for a long beat. Then he sighed dramatically. "God, you're such a decent guy, it's actually annoying."

"So… you're not mad?"

"I'm not mad," Hanamaki said, rubbing a hand down his face. "I just need to scrub my brain with bleach for a second because now I'm imagining you trying to impress my mom and—ugh, gross."

Matsukawa snorted. "I already impressed your mom. She gave me extra karaage last time I came over."

"That's because you helped her carry groceries, you manipulative giant."

They started walking again, Hanamaki shaking his head like the world had personally betrayed him.

"I can't believe you fell for my sister," he muttered. "You've seen her yell at me for stealing the last piece of mochi, right?"

"She was right, though," Matsukawa said casually. "You did steal it."

Hanamaki groaned. "Unbelievable." But a second later, he added, voice softer: "Just don't screw it up, yeah?"

Matsukawa looked over at him, serious now. "I wouldn't. Ever."

Hanamaki glanced sideways. "Good. Because if you do, I will text every embarrassing photo I've ever taken of you to the entire team."

"…You already do that."

"Exactly. Imagine what I'm capable of when I'm actually mad."

Matsukawa laughed again, and Hanamaki couldn't help but smile — just a little.

Masterlist

[arynxdxo]

Seijoh 4 as 1st years! part 2/4

This took me too long I’m sorry I had entrance exams goin on that I definitely failed, I am not getting into an engineering college dawg 💔🥀😍

Anyays, enjoy! Part 3 will be out who knows when! I have finals too!!!

Part 1 : https://www.tumblr.com/iwaizumilvrrrr/803788666534232064/seijoh4-as-first-years-comic-part-14

Post by @iwaizumilvrrrr · 9 images

💬 2  🔁 1  ❤️ 33 · Seijoh4 as first years comic!! Part 1/4

[airplanecrashingtowardstheground]

this is the only thing i'm contributing to the iwaoi agenda

[iwasdear]

I'm coming in with another thought about Matsukawa cus he lives in a penthouse in my brain and bro is not moving out any time soon

he did not truely grasp how big his meat was until he lost his virginity

sure he's not dumb he knew it was definitely something but not until he got a girl in bed did he realize his shtick was built different

and lemme say that did more than just inflate his ego, he was a changed man

And doesn't just slang it all willy nilly and expect his size to do all the work, he learned the motion of the ocean and was a certified sex god from that point forward‼

Not just cocky for cockys sake, he promises a good time and sure as hell lays it tf down too😼

On a similar note can I ask how you think all the seijoh 4 first times went? when? how? what do you think?

oh i definitely fuck with this thought, anon. he's not cocky just because he can be cocky, but it's because he knows he can be cocky. matsukawa isn't like those annoying mfs that are cocky because they think they're the shit. he is the shit. after that encounter where he lost his virginity, he became a god and nobody could stop him no more.

now, here is how i think seijoh 4z first time went ( with reader ) ★

oikawa had his first time at a party. since he's very popular, he gets invited to parties often. i feel like he def had no idea as to what the fuck to do, but i mean, you're not bound to knows when it's your first time, right? he was really excited about it, though, and spoiler: he came really fast! we understand, king. hormones are everywhere, there's a rush that's hard to ignore, its a first time sensation, how could he hold back? he had a round two after that because he reached his own high, but reader didn't even get to enjoy theirs, and let me tell you. his second orgasm hit him ten times harder. i know this messed up with his ego so he's been participating in every no nut november like a loser because he says it will help him last longer (it really doesn't).

mattsun had a pretty decent first time with a date, and it went absolutely amazing for both of them. the amount of stamina this guy has is insane. they met on a dating app, both of their profiles specifying that they didn't want anything serious, much rather looking for a quick hook-up. it was then when matsukawa realized his cock was in fact not your average dick. the fact that his huge buddy could make someone cry in pain fascinated him. my guy has morals so he held back so reader could adjust but god was his ego over the roof. ever since then, mattsun proudly carries a weapon between his legs.

makki had his first time in a damn club HANDS DOWN. unlike oikawa, who had the commodity of a (strangers) bed, hanamaki went at it in a bathroom. oh yeah. ngl i feel like he's a sucker for head, so they went with that first! he loved it, btw. lasted quite long but not too long, iykwim. then he proceeded to fuck reader on the sink. some clubs tend to have full body mirrors and my gut is telling this mf had a second round but this time full view on said mirror. the ones above the sink weren't it for him. out of the 4, i personally think makki is the most experienced. he knew what he was doing the moment they walked into that bathroom. if you're wondering, they waited for it to empty out and locked the doors and didn't let anyone in for a good two hours, teehee.

this one may be a little too biased because i love iwaizumi a little too much, and in my eyes, he's a gentleman. unlike the other 3, iwa had his first time with someone he was in a stablished relationship with at the time. it was actually quite romantic and beautiful and SIKE. hajime had his first time in the lockers. stressed from dealing with oikawa and his annoying fangirls, mattsun and makki holding him back from beating the shit out of his best friend, and just built up stress from other things. he was over it. the stablished relationship part is true. he asked reader to meet in the lockers a little earlier than the time practice usually ends because he heard from others (mattsun) that sex was a good stress reliever. by the way, iwaizumi was the last to lose his virginity. the gentleman part was also true because despite being someone who doesn't speak his mind outloud, my man still had the courage to confidently ask reader if they could do the deed right there and then. tbh i feel like he likes his privacy, and i mean, anyone could walk in any second, so they both went with the showers. great experience if you ask him, but he would NOT do it in an open space like that ever again.

© iwasdear | more thoughts are welcome!