In the dimming twilight of his unlit room, Ryosuke leaned against the headboard of his bed, listening to footsteps approaching his door from the next room.
After a few hesitant beats—
Knock, knock.
The sound echoed.
He tossed his smartphone onto the sheets and turned toward the door.
"Come in."
As he spoke, the door slowly creaked open.
"..."
"You made it."
His voice dripped with mockery. Manaka—his older sister-in-law who had abandoned her boyfriend to come to his room—couldn't meet his gaze. Yet, with deliberate resolve, she stepped inside and closed the door behind her.
She wore her school uniform: a blazer, skirt, and socks. Her large breasts, impossible to conceal, drew attention. Her waist curved into a neat hourglass shape. From beneath the short skirt peeked her plump thighs. Her navy socks-clad feet rubbed together awkwardly.
"Are you still cold?"
"..."
Manaka stood frozen, nodding slightly. Clutching her arms tightly, she accentuated the overwhelming presence of her full bust even through the knit fabric.
It's more than just the cold, isn't it?
Ryosuke couldn't clearly discern Takuma's condition. He sensed both of them climb onto the bed, but it had been quiet ever since. Takuma might even be dozing off.
In any case, Manaka had come to his room, leaving her boyfriend behind.
Of course, she must be prepared for what's to come.
"Come here."
With a gentle smile, Manaka timidly approached. As usual, she avoided his gaze, but she deliberately perched her knees on the single bed and slowly buried her face in Ryosuke's chest.
She didn't resist when he embraced her.
Her body was cold, but that wasn't the only reason for her slight shivers.
Ryosuke stroked Manaka's soft hair with gentle fingers, the way he would with Marin. It was hard to tell who was older this way—Manaka's body, so soft and pliant in his arms, so helplessly stirring his primal instincts, was undeniably a woman's body.
"We're doing something wrong, aren't we?" he murmured.
Manaka's shoulders shuddered.
"And we're about to do something even worse..."
He could feel her breath growing warmer against his skin. His palm brushed against her back as her breathing quickened, the rhythm of her breaths rising and falling. The texture of her knit vest beneath his hand, and beneath that, the cold metal of her bra clasp.
"Nee-san, look at me."
"..."
Finally, their eyes met.
Her expression was vulnerable, as if she might burst into tears at any moment. Only her cheeks burned with heat. He gently cupped her face and pressed his lips to hers.
"Mmm... Mmm..." Manaka moaned, her voice syrupy sweet, as if she'd finally received a long-awaited reward.
Then Ryosuke sneaked his right hand under her clothes, kneading her breasts and skillfully probing her weak spots with his fingertips.
"Ah... Nngh...!"
She writhed and gasped.
Even with such light caresses, her reactions were incredibly responsive.
"There... Ah! How do you know that spot...?"
She sounded delighted, but...
"If you keep making that much noise, the neighbors will hear."
"――――H?!"
"...You completely forgot about Nii-san, didn't you? What a terrible 'childhood friend' you are."
"That's not fair...!"
"I'm pretty terrible too, making you look like that, Nee-san. But I have no intention of stopping. You don't, either, do you?"
There was no reply—but that was a clear affirmative.
"As long as they don't hear, it's fine. Hey, will you make me feel good too?"
"..."
Manaka lowered her gaze to Ryosuke's lower abdomen, silently removed his pants and underwear, and then began:
"–nnchuu, chuu..."
She kissed the base of his penis with loving tenderness, her lips clinging to him.
"R-ugh... chup, nnchuu, chummm..."
Manaka's blowjob traveled from the shaft to the underside, then up to the glans. The ticklish pleasure quickly brought Ryosuke's penis to full erection.
Seizing the opportunity—or perhaps more accurately, unable to restrain herself any longer—Manaka lunged at the tip of his penis.
"Gujupu, nup, nopo, jupuu—gup, guupuuu!"
Perhaps because Ryosuke had warned her, she made no sound, her head moving up and down with single-minded devotion. But the intensity of her deepthroat, audible even without moans, was so violent it threatened to wake Takuma next door.
Even Ryosuke, usually so composed, was beginning to sweat from the pleasure.
"Was it really building up that much? Does sucking my dick make you happy?"
His harsh words only further aroused his older sister-in-law. She intensified her assault, using her tongue and hands to torment him. With each movement of her head, lewd wet sounds mingled with her sweet moans—this wasn't just fellatio; it was practically her own masturbation.
"Gulp, slurp, slurp—"
"If you keep that up, I'm going to come... You don't even need me to put it in your pussy."
Manaka's body twitched, and she looked up with a pleading expression.
"Haha, you're making it too easy. If you want me to fuck you, at least get into the proper position."
He sneered as he made his demand. Manaka climbed onto the bed, lay back, and spread her legs, bending her knees. The hem of her skirt was pulled up, revealing a glimpse of pale aqua underwear.
"Show me more."
"..."
Manaka turned her face away in silence, but obediently cradled her thighs, exposing the crotch of her underwear to him.
"H- Hurry..."
"You really want this, don't you? With me?"
"Ugh... Ugh..."
Her voice trembled, almost on the verge of tears.
"But Takuma—"
"Enough with the excuses."
Ryosuke's voice turned icy, making Manaka flinch.
"Ah... Ugh..."
"Never mind me or Nii-san. What about Nee-san? What do you want me to do with this?"
He pressed the head of his erect penis against her soft cleft through her underwear.
"Ah—!"
"Why do you look so eager? I haven't even said I'll put it in yet. Nee-san needs to beg properly."
"I... I..."
Squelch.
He could feel her wetness against his glans, but he held back from further stimulation.
Then,
"Haa... Huh... Ugh..."
"Keep your hips still, okay?"
The frustrated older sister shamelessly began to sway her hips, seeking pleasure. She rubbed her lower abdomen against Ryosuke's penis, letting him stroke her labia and clitoris. The love juice seeping through her underwear marked his penis as if claiming it.
"Hah... Nii-san... Ryosuke... Hnn... Ugh..."
"Isn't this embarrassing, acting so lewd with your younger brother? What do you think your brother would say if he saw you like this?"
"N-no... I won't let him see... never!"
"Your voice is pretty loud, you know."
In the room across the wall, Takuma was asleep.
Manaka desperately tried to suppress her cries, but the friction of his penis against her was eroding her resolve.
"Ugh... Ah... Stop... Already... Hurry—"
"If you want me inside you, spread your legs."
He lowered his voice, his words dripping with malice.
"You want it, don't you? To throw your brother aside and fuck his younger sibling... Show me with your words and actions."
"Ryosuke..."
Tears welled in the corners of Manaka's eyes as she hooked her fingers into her underwear.
"P-put it in... I've always wanted you here, Ryosuke, always and forever..."
"Are you sure it's not Nii-san you want?"
"Yours... Ryosuke is better... I like being fucked by Ryosuke more than Takuma... I like it... Ngh! Ahh!" She gasped sharply.
Ryosuke invaded his older sister-in-law's exposed depths. Despite her melted state, her tight, slick walls swallowed his erection to the root, their ridged insides clenching him in a snug embrace.
"Ah... Naaaah...!" Manaka stifled her cries, trembling with ecstasy.
"No way! You came just from penetration? You're too weak, Nee-san. Even my girlfriend lasts longer than you."
"~~~H... B-but, I'm better suited for Ryosuke than that... that girl! I'm the one who really fits you—"
"What a delusion! You're the lowest kind of bitch, cheating on your boyfriend and getting off on your brother fucking you!"
Yet, there was truth in her words.
Manaka's pussy, which had taught Ryosuke the pleasure of sex, had certainly molded perfectly to his shape.
Just as she derived pleasure from it.
Ryosuke, too, was being pleasured by the soft folds of flesh that gripped him tightly from base to tip. The sensation was so intoxicating that he nearly lost himself in his older sister-in-law's voluptuous body.
Not yet...
Gritting his teeth, Ryosuke resisted the temptation and roughly grabbed Manaka's hips, thrusting into her weak spots with precision.
"Haaah?! Ah, Aah, Nuuu—"
Her disheveled uniformed older sister bit down on the edge of the pillow to endure it, but her love juice flowed more profusely, and muffled, animalistic moans escaped her lips.
"I-I'm gonna... I'm cumming! Ah, uuuu!"
Ryosuke tore open Manaka's disheveled upper body. He hiked up her knit vest, ripping her uniform blouse, camisole, and bra apart. As her plump breasts were exposed, a thick, sweet scent wafted out.
When he seized her breasts with both hands, their softness and resilience alone stirred his primal instincts.
He tormented her hardened nipples while thrusting his hips—the creaking of the single bed, though faint, must have echoed into the next room.
Yet Takuma, asleep in the adjacent chamber, likely couldn't possibly dream that his childhood friend—his older sister—was being defiled by his younger brother right beside him.
"Nee-san, I'm coming."
By then, Manaka's mind was no longer registering sound.
She had fallen completely into the role of a bitch, arching her back with every thrust to milk his cock, her rationality utterly abandoned.
Having forgotten her duty as an older sister and her conduct as a family member, she was reduced to a mere vessel for carnal pleasure, and it was into this womb that Ryosuke released his seed.
"–h, ugh..."
His hips trembled deep within her. The violent spasms were so intense he could feel the thick, abundant semen surging out.
Even as he climaxed, he kissed her, covering her mouth. He did it to muffle her loud moans—and to stop himself from groaning aloud.
"Ryou... nmbu... Naa... nju... juururu..."
Instinctively, they ravaged each other's lips, pressing their spasming lower bodies together. The sex of the sister and brother, transformed into beasts. Their connected genitals melted together in a sensation so intense it bordered on pain. A bottomless pleasure.
After a long, drawn-out climax, Ryosuke propped himself up on one elbow and looked down.
"Haha... Nee-san, you look terrible."
He smiled and spoke to Manaka, uncertain if she was even conscious.
"Want to take a shower together? It's okay. Marin just happened to (...) go out for a walk a moment ago. As long as we don't wake Nii-san—"
Manaka's expression remained dazed, but she unmistakably nodded.
"I... go..."
*****
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