Chapter Text
It's Osomatsu’s birthday. Well, ok, his birthday was yesterday but you had work so he’s coming over tonight instead. And, as if him changing the ringtone for himself in your phone to “Birthday Sex” wasn’t obvious enough, he’s been dropping hints all month about what he’s interested in. And it’s lingerie.
He left a dog eared copy of a Victoria’s Secret catalog on your kitchen table. You leafed through the magazine idly while eating breakfast, nearly choking once you see he had colored in a white bra sloppily with a red marker and drew a heart around it.
So when you open the door for him and he sees that you’re wearing some sloppy pajama shorts and a baggy tshirt, his expectant smile drops and he leans forward to peek around your front hall, searching for something more.
“Is that it?” He sounds hurt and a pout tugs at his lower lip. Clasping your hands around his neck, you pull him inside and press a kiss to his cheek.
“Don’t judge a present by its wrapping.” You hum into his ear, and his hands are already snaking under your shirt before you finish the phrase. You can't tell if that's because he was anticipating your surprise or just an automatic reaction to any kind of affection from you. His fingers freeze when they graze the lacy trim of your bra, his breath stuttering in your ear as you feel his smile spread against your face.
“Yes! Yes, yes, yes!” He chants. You step back and watch him pump his fist in victory, his cheeks already flushing. There’s something so sweet about the way he smiles that reminds you of someone more innocent, but the thought is pulled from your head as his hand cups your ass and he rubs his lips along your neck.
“You looked so disappointed for a second there!” You’re laughing but the rumble in his throat makes you tilt your head so he can have better access to the skin of your collarbone.
“Listen,” he pulls back, a wide grin plastered across his face. “I trimmed my pubes for this.”
“Wow.” You extend the syllable sarcastically, but he’s too pleased with the situation to sass you back. He bends over and grabs your legs, and with a yelp you’re hoisted over his shoulder as he scurries over to your room. His shoulder digs into your belly uncomfortably but when you complain he just smacks your ass.
“It’s my birthday!!” He cheers, and you can’t tell if that was a justification for his behavior or a general reminder, just so he can make sure that you know and don’t forget tonight is about him.
“Your birthday was yesterday, you complete and utter buffoon!” He just slaps your ass again before dumping you onto your bed. You haven’t seen someone be this excited for their birthday in years.
Before you can make another teasing comment, he’s slamming his lips into yours and prying your legs apart to settle between them. You release a pleased sigh around his tongue at the comfortable warmth of his torso bleeding through his sweater and the feeling of his weight on top of you.
The noise is sucked out of your lungs in a desperate gasp as he shifts forward and slides his crotch against yours, and he mirrors the sound as he rocks his hips again. It’s not a great angle for you, but he’s getting everything he needs and the way he pants into your ear makes your heart jump into your throat regardless.
One of his hands fists the pillow beside your head to support himself over you as he continues to rut against you. His expression is half crazed, his tongue lolling out lazily in contrast to his sharp and purposeful movements.
The skin of your face burns as he rakes his eyes over your body, his gaze settling on your chest. There’s something so unfortunately erotic about how he looks at you when he’s turned on -- the loud, clamoring desperation in his eyes that betrays how badly he wants you, right now, however he can get it. He moves a hand to your breast, but instead of his usual rough gropes and squeezes, he lightly palms over the cotton of your shirt, feeling the fabric underneath.
“Fuck.” He punctuates the word with another sharp roll of his hips, the lump in his pants getting decidedly more pronounced as his fingers trace the lacy pattern of your bra. Seeing him come undone from so little is making your breath come out unevenly and the warmth between your legs pulses every time he humps against you. Your fists clench tightly in the back of his shirt, trying to pull him back down against you but he’s too enamoured with the sight of you sprawled underneath him to give in.
“Osomatsu, c’mon.” You mewl, a little scattered and acutely in need of a better angle. He’s not usually this deliberate, his hands fast and sloppy, and his kisses exclusively to enable more groping.
“No.” His voice jumps a bit as he grinds against you again, your own breath hitching in response to the pressure against your crotch. “I’m having fun.” He runs his tongue over his lips and doesn’t tear his gaze away from where his hand is running over your chest, but you know he’s listening to you by the way his fingers squeeze around your breast and he bears his hips down harder every time you gasp.
“Oso…,” you elongate the sound, knowing how weak he is when you whine (he’s not usually good enough at pacing himself to get you to beg, and not generally skilled enough to tease). You tilt your hips off the bed, leaning against his weight so he can feel the way your vagina could slot with the tent in his pants if he’d just stop faffing about. The contact makes him groan, his eyes rolling back slightly and his head hitting your shoulder as he slumps forward. His hands grip your hips, trying to keep you at that lovely spot for him to grind on, but you can’t make enough purchase with your legs to maintain the position for long.
He huffs as he pulls away, and you’re expecting him to be bratty and complain but he just sits back on his knees and tugs you into his lap, tucking his hands under your legs and pressing your knees to your chest before leaning forward to push his weight into you again.
You feel ridiculous, your stomach squeezed uncomfortably underneath your thighs. Osomatsu pauses, giving you a chance to protest, but when you don’t say anything he grins through half-lidded eyes and leans his face against your raised thigh and takes a really good look at you.
With your knees squeezed to your chest and the support of his legs underneath you, your shorts are pulling tightly against the curve of your mound and exposing most of the skin of your ass. You’re honestly impressed that he could find the most compromising angle for even the sloppiest of outfits but at this point your clothes are feeling too warm and you’re too needy to poke fun at him.
“Dang, you’re just bussin’ it wide open for me.” He croons. His voice always has the inflection of a chuckle in it. You grimace, wanting to admonish him for saying that kind of shit to you Jesus Christ but it’s his birthday, and you’re not going to pretend the stiff lace digging into your ass and the way he looks at you aren’t making you feel a little sexy and debauched. He can tell you’re biting your tongue because he sits up a little and smiles even wider. As much as he loves exchanging quips with you, he’s uniquely delighted by leaving you speechless.
“Hey, want me to take your clothes off?” His breath comes out sharply through his nose.
“No, I bought these lacy undies for myself, so I can look at it in the mirror when I’m all alone.” He’s testing your patience and both of you know it.
“Too bad! I get to unwrap my present whenever I want!” He ignores your sarcasm, but his expression sharpens for a second once what you said sinks in. “Ok, that’s really hot though.” He adds, panting slightly as he rocks his hips into yours again.
You give him a look, really trying to communicate how needy and impatient you’re getting, even biting your lip for emphasis, and his mouth presses into an anticipatory smile as his eyes dart downwards from your face. Sliding his hand off of your chest, he moves down to your shorts, tucking a thumb underneath the loose cuff of fabric around your thigh. He raises it slowly, lazily, until he peeks a thin strip of red lace.
He laughs. “Haha, that’s my color.” He draws out the laugh teasingly, like it’s supposed to be embarrassing that you did something for him, but you are, in fact, bussin’ it wide open and can’t believe he’s pulling this shit.
But his eyes dwell on the exposed sliver of fabric, his smile softening at the edges the longer he stares.
“Mine.” The word comes out a little strained, like his throat is being squeezed, and the sound makes your heart jump. It’s rare to see him flustered. He’s usually fine if he thinks he knows what he’s doing, and he’s stupid and confident enough to usually think he knows what he’s doing.
“Yeah.” You say, swallowing thickly.
He practically whoops as he releases your legs, his arms wrapping around you and his face burying into your neck. “Mine!” His husky voice is muffled by the mouthful of skin he’s trying to suck and bite at, and his hips are bouncing frantically into you. The sweat of his forehead presses behind your ear and he keeps repeating, “mine, mine,” the words erratic and desperate and unusually earnest.
You try to move your arms, but he’s coiled around you so tightly that you can’t. His words are cut into pieces as his breathing gets more irregular, air hitting your neck in rough pants as he starts to drool against you. He squeezes you tighter and jerks against you in a stuttering motion before he pushes against you for a long moment, his breath choked in his lungs.
You suspected what had happened by the pulse of his cock through the fabric of your pants, but the wet way his jeans slide against his skin as he pulls away from you confirms it.
“Ahh,” he exhales loudly, rolling off of you. His eyes are nearly shut and he looks euphoric and sweaty. “That was great.”
You just look at him incredulously, even though the gesture is lost on him in his blissed out state.
“Osomatsu,” you say, propping yourself up on your elbows. “We didn’t… I mean, are you… I’m still fully clothed.” You’re picking your words carefully, because you really don’t want to make him feel bad for, well, feeling good.
“That was great.” He repeats, his eyes falling completely shut as he tosses his hands above his head so he’s flopped across the bed in the most lax position possible. His smile is closed and tilts up at the corners unevenly.
“Do you know how much these things cost?” You say. He cracks an eye open and you tug one of the bra straps out of the neck of your shirt to show him.
“We can use ‘em again.” His voice is warm and comfortable, the words slurring together slightly. He rolls over and slings an arm over you, humming softly as he presses his face into your chest.
“But I got them for your birthday.”
“My birthday was yesterday.” The warmth of his breath sinks into your shirt and spreads across your as he talks.
You snort and he nuzzles deeper into your chest. With a sigh, you fall back against the mattress. He's such a fucking dork.