Natsuki tries Anal with Anon! (Lewd, duh)

“Are you sure this is safe?”
Natsuki covers her chest loosely with her thin arm, blocking your view of her nipples, which rested on tiny mounds protruding from her chest. She sat on a lavender bed, her legs crossed and her other hand twiddling the curls of the blanket between her thumb and forefinger.
Spare for her socks, which you requested she keep on, she was completely naked, trying her best to keep her blushing red body from exposing too much to her partner towering above her.
“It’ll be fine. I’ve read a ton of stuff about this, and it shouldn’t be too much of a stretch. You did prepare first, right?”
“W-Well…” Natsuki looks away, her mouth forming a nervous smile as she thinks back to her ‘preparations’, most of which were her scrubbing herself and convincing herself that she was doing it for you.
She had refused the idea of “preparing” that Anon had told her about though, at least when she agreed to do it. The thought of putting something in there, much less her own fingers was too lewd for her to contain, and her face would show more color than the overextravagant hairstyles found on the covers of her favorite manga.
“Y-yeah, cleaned up and everything!” Natsuki turns towards you, but her line of sight locks to your girth. While Natsuki had been absorbed in her flashback, you had dropped pant and were currently standing bare, your member pulsating in anticipation.
Natsuki stares at your girth, dreading the thought of it trying to force its way inside her. Her sphincter clenches, and she shudders, her hand clenching the blanket.
You pull the condom out of its packet and roll it down the length of your member. Natsuki’s eyes trail the motion of your hands as you finish up, gulping as she watches your cock finish its tantalizing preparations.
“A-Anon are you sure this is going to fit?” She stutters, unable to move her eyes away from the massive rod in front of her.
“I’m sure it’ll be fine. Here, grab this pillow and rest against it, squeeze it as hard as you can when it comes in, and don’t clench up down there. You won’t feel any pain, I promise.”
Anon guides Natsuki to roll over and ease into position. Once she obliges and gets on her knees, you get a full view of her tiny bottom. Slim and linear hips outline her supple, bony cheeks, and your eyes trace around the edge of her bottom to her crack, her slit and backdoor becoming visible as she leans down, her elbows pressing into the side of the bed.
You place your hands on the gentle, tiny curves of her hips, and inch Natsuki forward towards you.
“Can you lower yourself a bit more?” Natsuki obliges, bending her knees to bring her ass down to the right level.
Her slit brushes past the tip of your penis, and like a mouse started by a cat, she jerks back up with a squeak.
“Anon I’m really not sure I’m ready for this can we just gimme a second I don’t know if-“
Anon leans over and grasps Natsuki’s hand, and she squeezes it. You wrap your other arm behind her and hug her tight, and she lets a sigh loose.
“I… trust you. Just, be gentle, okay?”
You can’t help but chuckle, hearing the endearing words of consent coming from your partner. “You’re so cute when you’re brave.”
“Don’t push it.” Natsuki spits back at you, her eyes darting to yours with a playful glare.
You grab a bottle of lube from the bedside table, and apply a generous amount to your member, massaging your member with your hand and getting it ready for her entrance.
You climb over her just a bit more and slide your cock into her backdoor. As you do so, a low, murmuring groan claws its way out of Natsuki’s lungs, and she squeezes the pillow under her with all her might, contorting the shape to the position of her crossed arms.
You look over to Natsuki once your member is fully buried inside of her. “Hey, you alright?”
“D-don’t…” Natsuki’s breaths are already ragged, and your heart begins to fill with lead.
“Don’t… fucking stop… keep going…”
Finally catching a glimpse of Natsuki’s face, you notice her jaw agape. Drool leaks from the corner of her bottom lip, and her eyes are clouded, desperately trying to hold on to any semblance of consciousness.
Taking the hint, you start to move, inching out, then pushing back in. her backdoor caresses your member in a warmth that chokes it, squeezing the life out of it.
“Faster…” Natsuki groans through ragged breaths and incomprehensible moans, her mind barely holding on as it succumbs to this newfound pleasure.
You pull out halfway, and start to piston, your hips putting in more work now that she’s grown used to you inside there.
Every plunge into her is greeted with louder, high-pitched moans, muffled by the pillow shrouding her face.
Her slit, soaking with her juices, runs down her leg. Natsuki notices the dripping sensation and moves her fingers to her bean, her fingers scrounging for it. Once she finds it, she starts to swirl her fingers around it, screaming in delight of the combined pleasures of both holes.
“Fuck, Anon, I’m gonna cum!” As she screams out in pleasure, you too feel the familiar build-up, and start to piston faster, her insides clinging to you and wringing you dry.
“I’m gonna cum too!” you plow her into the bed, your hips bucking faster than you thought you could, and Natsuki screams out, her fingers dancing over her clit, finding each weak spot.
The build-up reaches out from inside and moves to the tip of your penis, then bursts outward, filling the condom. Natsuki shudders as she feels the rubber expand, and she collapses, your dick sliding out of her with a resounding ‘pop’.
You fall onto the bed next to her. Natsuki turns towards you, and kisses you, her tongue draping into the inside of your mouth.
You pull her into you, deepening the kiss. You feel her tiny, erect nipples, press into your chest like blunt needles. Her tongue reaches as far as it can, exploring every inch of your own.
Her left hand moves to your cheek, caressing it with her hand, her finger catching stray strands of your hair. Her right hand moves down your chest, to your ever-stiffening member, and presses her thumb and forefinger to the condom.
She slides the condom off and tosses it across the room, then wraps her legs around you. Still kissing you, she places her front entrance over you, and impales herself onto you, moaning into your mouth.
Your hands move to her hips, and hers to the back of your head, and you pump without care, your animalistic instinct taking over your lust-warped mind.
Natsuki only moans more, and she uses her legs to squeeze you, trying to force herself on you as much as she can.
In barely anytime at all, you feel your muscles tighten, and your cock twitch. You pound into her, and she screams your name.
“Anon, I’m gonna cum again, fill me up, please cum in me!” Natsuki, too dazed to understand what she’s saying, begs you as she stares into your eyes. A lustful gaze bores into your eyes as she pulls away, her tongue bouncing around outside of her lips as she bounces on you.
You hilt yourself on her, plunging in your cock as your cock plunges its seed into her. Her fingernails claw into your neck as she moans your name one last time, finishing with another shudder.
Natsuki goes limp, her eyes shutting and her lungs gasping for air.
“That… was so much fun…” Natsuki buries her face into your chest, and your caress her head with your arms, smelling the strawberry-scented sweat of her hair. You smile, feeling the pulse of her heartbeat in-sync with yours.
You drift off to sleep, your partner already passed out smiling in your arms.