Ren's hips snapped forward again, burying himself to the hilt inside his older sister's tight pussy, dripping heat. The old bed groaned beneath them, metal springs squealing in rhythm with Kyouka's breathless cries.

"Nnghh~Ren! You're… you're so deep!" Kyouka gasped, her nails digging into the thin mattress. Her body trembled, half from the aftershocks of cold, half from the sudden, overwhelming fullness of her little brother's cock stretching her virgin walls.

Who could've thought this would happen? Kyouka had never seen Ren as a possible sexual partner until recently, and now that same foster brother of hers was deep inside her, stretching her pussy walls.

Ren smirked against the back of her neck, teeth grazing her skin. "Took mine, huh? Cute. But who's the one getting fucked stupid right now, big sis?"

He pulled out slowly, deliberately, letting her feel every thick inch drag along her sensitive insides, then slammed back in hard enough to jolt her whole body forward. Kyouka's moan cracked into a squeal, her back arching like a bow.

"Ahn! Don't—don't say embarrassing things!" she whimpered, but her hips were already pushing back greedily, chasing more.

Ren chuckled darkly, one hand sliding up to fist her long silver hair, tugging her head back so he could growl into her ear. "Embarrassing? You're the one soaking my cock like a desperate little slut the second I put it in. Look how wet you are, big sis. Listen."

He pulled out again and thrust in with a lewd, wet squelch that echoed in the empty shack. Kyouka's face burned scarlet.

"R-Ren…!"

"Say it," he teased, rolling his hips in slow, filthy circles, grinding against her deepest spot. "Say you're my needy big sister who loves her little brother's dick."

Kyouka bit her lip, shaking her head stubbornly even as her pussy clenched around him like it was trying to suck him back in. Ren clicked his tongue and stopped moving completely, buried balls-deep but perfectly still.

"Ren...move! Please!" she whined almost immediately, trying to rock back against him.

"Not until you say it."

She lasted three whole seconds.

"I-I'm your needy big sister who loves her little brother's dick!" she blurted, voice cracking with shame and lust.

"Good girl." Ren rewarded her with a brutal thrust that punched the air from her lungs, then another, and another, setting a punishing pace that had the headboard banging against the rusty wall.

The shack filled with the obscene sounds of skin slapping skin, Kyouka's broken moans, and Ren's low growls. He reached around to pinch her swollen clit between two fingers, rubbing roughly.

"Come for me, Kyouka. Come on your baby brother's cock like the pervert you are."

That did it. Kyouka screamed, whole body seizing as her orgasm tore through her, pussy spasming wildly around Ren's pistoning shaft. Juices gushed out around him, dripping down both their thighs.

Ren didn't stop. He fucked her through it, prolonging the climax until she was sobbing from overstimulation.

"Too much—too much, Ren, I just came—!"

"You can give me another," he panted, pulling out suddenly. Before she could complain about the emptiness, he flipped her onto her back and spread her legs wide, hooking them over his shoulders.

Kyouka's eyes widened. "W-wait, this position—"

Ren drove back in without mercy, folding her nearly in half. The new angle let him hit even deeper, the fat head of his cock kissing her cervix on every thrust.

"Look at you," he groaned, watching her breasts bounce with every slam of his hips. "Tits jiggling, face all fucked-out… you're so pretty when you're getting ruined, big sis."

Kyouka could only whimper, hands scrabbling at his back, leaving red trails. Ren leaned down, capturing a nipple between his teeth and biting just hard enough to make her yelp.

In midst of all this, she had to wonder who is this man? Is he even a man? If she didn't know any better she would have thought this was a woman because of how dominating and amazing he is, something Kyouka never thought possible for a man.

"Mark me," he ordered suddenly, voice rough.

Kyouka blinked through teary eyes, then surged up, latching onto his neck. She sucked hard, tongue swirling, until a dark purple bruise bloomed under her mouth. Satisfied, she moved to his collarbone, then his chest, leaving a trail of love bites.

Ren hissed in pleasure. "Fuck yes."

He pulled out again, making her whine, then spun her around onto all fours. Kyouka barely had time to brace herself before he mounted her from behind like an animal, one hand pressing between her shoulder blades to push her chest down into the mattress, ass high in the air.

"This is how beasts do it," he growled, slapping her ass hard enough to leave a handprint. Kyouka squealed. "And right now, you're my bitch in heat."

He slammed back inside, the new position letting him go even deeper. His balls slapped against her clit with every thrust, driving her wild.

"Ren—Ren—too deep, I'll break—!"

"You won't break," he snarled, grabbing both her wrists and pinning them behind her back with one hand, using them like reins to yank her back onto his cock. "You'll take everything I give you."

Kyouka's second orgasm hit like a freight train. She screamed into the mattress, whole body shaking, pussy trying to milk him for all he was worth.

Ren gritted his teeth, pace turning erratic. "Shit—gonna cum, Kyouka—Take it all inside to warm your body."

"Inside!" she begged shamelessly. "Fill your big sister up, Ren—give me everything!"

That tore a guttural groan from his throat. He buried himself to the root and exploded, thick ropes of cum painting her insides white. Kyouka moaned feeling every pulse, her walls fluttering around him as if trying to wring him dry.

They collapsed sideways, still joined, panting harshly. Ren's cock twitched inside her, plugging his seed deep.

For a long minute, only their breathing and the wind outside could be heard.

Then Kyouka let out a weak laugh. "It is really warm baby...look we stopped shivering."

Ren huffed a tired chuckle, kissing the bite marks on her shoulder.

She turned her head to glare half-heartedly over her shoulder. "Are you sure you are a man, Ren?"

"Your man," he corrected, grinding lazily inside her again. His cum leaked out around his shaft, making obscene squelching noises as he stirred it deeper.

Kyouka shivered. "Again…?"

"We're not done until the sunrise," he whispered darkly, fingers already sliding down to play with her oversensitive clit. "I'm gonna fuck you on every surface in this shack. Then I'm gonna fuck you against the wall. Then on the floor. Then—"

Kyouka cut him off with a desperate kiss, rolling her hips back against him.

"I might be injured but let me show you what it means to be an elder sister, my little brother."

Kyouka's lips crashed against Ren's, hungry and demanding, swallowing his surprised grunt. She shoved him flat onto his back with a palm to his chest, the old mattress creaking under the sudden shift. His cock slipped out of her with a wet pop, still hard and glistening with their mixed juices, bobbing against his stomach.

"'My man?" she smiled like a devil, voice low and dangerous as she straddled his hips. "Cute. But right now, little brother, you're the one who's going to lie there and take it."

Ren smirked up at her, silver bangs sticking to his forehead with sweat. "Big words from the girl who just begged me to breed her like a—"

She slapped a hand over his mouth, nails digging lightly into his cheek. "Shush!" Her other hand wrapped around his slick cock, squeezing until his hips jerked. "You had your fun. My turn."

Kyouka rose on her knees, guiding the swollen head to her entrance. She sank down in one brutal drop, taking every inch until her ass met his thighs with a loud slap. Ren's muffled groan vibrated against her palm.

"Fuck—Kyouka!"

She lifted her hand just enough to let him speak, then immediately rolled her hips in a vicious circle, grinding her clit against his pelvis. "That's Onee-san to you tonight, baby."

Ren's eyes flashed with defiance.

"Not gonna say it...huh!" She grabbed both his wrists and slammed them above his head, pinning them with one hand, her womanly-strength making it effortless. The other hand fisted his hair, yanking his head back to expose his throat. She bit down hard right over the hickey she'd left earlier, sucking until fresh blood rushed to the surface.

Ren hissed, cock jumping inside her. "Shit! you're gonna leave a mark people will see—"

"Good," she growled against his skin, licking the bruise. "Let them know my little brother's addicted for his big sister's pussy."

She started riding him hard, no warm-up, no mercy. Her hips slammed down again and again, the wet smack of her ass against his thighs echoing through the shack. Every time she bottomed out, she clenched deliberately, squeezing him like a vice.

Ren bucked up to meet her, teeth bared. "That all you got? Thought you were gonna break me, Onee-san."

Kyouka laughed, breathless and cruel. She released his wrists only to rake her nails down his chest, leaving ten angry red lines from collarbone to abs. "Still talking? Guess my little brother got attitude."

She shifted forward, planting her knees beside his ribs, changing the angle so his cock dragged against her front wall with every bounce. Her heavy breasts swayed inches from his face; she grabbed one and shoved the nipple into his mouth.

"Do it baby!" she ordered. When he latched on instantly, tongue swirling, she moaned approvingly. "Good boy. Keep that mouth busy while I use your cock."

Ren grazed the sensitive bud with his teeth in retaliation, making her gasp. She retaliated harder, lifting almost all the way off before dropping down so hard the bedframe rattled dangerously.

"Fuck—!" His hands flew to her hips, fingers digging in.

"Did you learn your lesson? Your onee-san is the one in control now... From today onward, I'm going to fuck you every single day: early in the morning, before breakfast, before lunch, before sunset, before sleep... I won't let you rest even once, MY LITTLE BROTHER!"

Ren could clearly see both Kyouka's love meter and the raw affection in her eyes skyrocketing.

"Looks like I've captured another yandere..." Ren muttered under his breath, already knowing it was going to be a very long night for both of them, as he also felt something else, like a new power raging inside him.