*****
In the changing room, I stripped Manaka-chan's sweat-soaked uniform. With each layer of clothing and underwear removed, the scent of sweat mixed with pheromones grew stronger.
"Aren't you cold?"
"...No. Ryosuke, take off your clothes too..."
My sister gently touched Ryosuke's skin with tender hands.
But it was fleeting. She bent down, pressing her lips against his chest.
"Mmm, chu, chum..."
Her estrus hadn't subsided. She savored his skin, his sweat, as if it were a reward, her lips and tongue thoroughly enjoying the taste.
Gradually, she lowered herself further, thrusting her knees forward, and lunged at his still-erect lower body.
Unmindful of the fact that just moments ago, his cock had been inside her—no, as if using that memory to fuel her arousal even further—she moved her head wildly, cheeks hollowed as she sucked hungrily.
"–Gup, jubo, gub, gub..."
"Can I finally cum in your mouth this time?"
"Mmmgh, gurgle, gurgle, gurgle..."
The deepthroat, reaching the back of her throat, spurred my orgasm. My penis pulsed violently, spurting semen.
"–Ngh! Mmm, gurgle, gurgle, gurgle..."
Despite the apparent discomfort, Manaka continued sucking with relentless intensity, as if determined not to leave a single drop of semen in my urethra.
"You seem happy, Nee-san. I'm enjoying myself too."
I stroked her hair in sympathy. She nodded slightly, her face a complex mixture of shame, guilt, and bliss.
A face she'd probably never shown Takuma.
The roles were reversed now.
When Takuma first came to this house, he'd glanced at Ryosuke and the others downstairs while Manaka and I indulged in sex upstairs.
And now, my Older Sister-in-law was reduced to this state.
I'm drowning in the sex with my younger brother, finding joy in serving him.
...I don't resent Takuma at all. I think he's a good person.
But. Ryosuke was certain he felt something from Manaka's expression that he couldn't get anywhere else.
"Ryosuke...!"
Manaka swallowed the remaining white fluid in her mouth, stood up, and leaned over the sink, arching her hips back. Her plump buttocks, as full as her breasts, were slick with sweat, love juice, and the white fluid Ryosuke had released.
"Come on, please, Ryosuke... I can't... I need you inside me—ah, Ahh!"
He thrust his still-hard penis into her, and Manaka's entire body shuddered with pleasure. The alluring curves of her hips and back. Her hair was disheveled and sticking to the back of her neck, but she paid it no mind.
In the mirror, Manaka's face twisted into a lewd expression.
"Feels so good... Scratching like that... Ngh... I love it there—"
"Better than Nii-san?"
"Ryosuke feels better! I've never felt anything like this before— Aahh! I'm gonna... I'm gonna come again! Hiaah! Faaaah!"
Not a trace of restraint or endurance remained in her. Watching his sister climax helplessly under his thrusts, Ryosuke fucked her with a mix of contempt and sympathy.
The encounter couldn't possibly end in the changing room alone.
As they entered the bath, Manaka stepped forward and pressed herself against him. She covered her breasts with soapy lather and clung to him.
The soft, slick feel of her flesh.
"Does that feel good, Ryosuke? Ryosuke... Mmm... Ahh..."
"I can feel my own nipple throbbing more than yours. Nee-san, you're way too turned on."
"But, but—" She gazed at him with a fawning expression. "Just seeing you, Ryosuke... Just touching you..."
"Should I keep going like this?"
She nodded, and he pulled her hips closer, adjusting their positions until his glans parted her labia. He probed the slick, fleshy sea for her vaginal opening—
"Ah! H-ah, Ah...!"
"It slides right in, doesn't it? Your pussy, Nee-san, has gotten used to sucking me off, hasn't it?"
"Ugh, Anh...! Aah, so good! You're hitting every single spot!"
"That's what I mean—you're getting too worked up."
Still standing, Manaka began thrusting her hips rhythmically. Her body, slick with soap and fluids, glistened. Then, she pressed her lips to his.
"Hmm, njuu, leuu..."
Skin against skin, mucous membrane to mucous membrane. Steam rose from the shower, which had been left running, and Manaka's moans echoed through the room.
"If you want it that badly, I'll sit down."
Still connected, he lowered himself onto the shower chair.
"Do whatever you want."
Manaka, no longer hesitant, began grinding her hips. Her slick folds writhed, squeezing his penis as if to say, Take this.
"Ah...! Ryosuke, Ryosuke...!"
"Good, that feels good. But if we keep going like this, I'll end up coming inside you again."
"–...! Just...! Let your semen flood my uterus...! It feels so good—that's the best! I love it, I love it so much! Give me your sperm, shoot inside me...!"
In response to her tightening flesh, he mercilessly thrust his seed deeper.
"Ahhhhh?! It's... it's... it's dripping down my uterus, coming out of my pussy...! My brother's sperm is inside me...!"
"Haha, you're really the worst, Nee-san."
"I'm sorry, I'm so sorry! I'm cheating on you, getting fucked by another man, and I'm cumming...! I'm ruined, I'm sorry...! Hnngh, hah, Aaaaaah...!"
Ryosuke embraced her trembling, feverish body as it convulsed violently.
"I won't let you escape. I'm going to keep fucking your pussy until you've had enough—brace yourself."
"Please, please...! More, more—"
He grabbed her soft buttocks, thrusting upward from below, driving Manaka to climax repeatedly. With each thrust, he felt thick, white fluid ooze from their joined flesh.
"Maybe you came here for this, Nee-san."
"...Huh?"
"So that I can be violated by me... so that I can be happy."
Ryosuke could feel Manaka trembling from the core of her body.
He felt the same way.
It wasn't fear or regret.
Just the shuddering tremors of a purely sweet, clumsy, and faintly dark pleasure—
A relationship neither familial nor romantic, but twisted. The two of them ravaged each other's bodies as if trying to merge. Their minds held no trace of family, of Manaka's childhood friends, or anything else.
*****
"Alright, let's take the photo."
Father stood facing them, holding his smartphone.
March.
After Manaka's graduation ceremony.
Manaka, having returned home with her parents, was to have a commemorative photo taken in front of the Shito family house. Ryosuke and Marin were dragged out of the house as well, and then—
"By the way, am I really allowed to be in this picture?"
Takuma was there too.
"Am I not just going to ruin the family photo?"
He didn't seem particularly embarrassed. That natural demeanor was one of his defining traits.
Then Father laughed,
"Takuma-kun, you're practically family now. I'll be counting on you to look after Manaka-chan in the future."
"Does that mean I can call you 'Father-in-law' now?"
"You cheeky thing, ha ha. I suppose you can. What do you think, Manaka-chan?"
"Huh? Oh, um... yes. Sure..."
Manaka stumbled over her words, and the two men laughed, assuming her hesitation was due to shyness.
Only Ryosuke knew the truth—that her flustered pause was tinged with guilt. Or rather, Ryosuke and his younger sister both knew.
The first photo was taken with Manaka and Takuma in the center, flanked by Ryosuke, Marin, and their stepmother.
When it came time to include the father in the next shot, Marin suggested, "Takuma-san, would you take the photo for us?"
"Sure, no problem."
Takuma smoothly pulled his phone from his pocket and switched places with his father.
This time, the parents stood at the back, while the siblings lined up in the front.
"Nii-san, please stand in the middle."
"Why me?"
"By age order."
Ryosuke stood in the center, Marin to his right, and on his left—
"..."
Without meeting anyone's gaze, Manaka turned toward the camera—toward Takuma—and stood up.
"Everyone, come closer, come closer!" Takuma urged with a cheerful grin, gesturing for them to gather.
"Apparently," Marin said, then threw her right arm around Ryosuke in a clingy embrace.
"Haha, you've become a total little sister, Marin-chan."
"Yeah. Thanks to Takuma-kun— Hey, Nii-san?"
"..."
Her suggestive tone didn't faze Ryosuke in the slightest. Though Manaka beside him seemed to react differently.
Ryosuke deliberately shrugged dramatically.
"Well, we're so close we annoy each other with our clinginess every day."
"You make it sound like a burden! You're secretly thrilled, aren't you, Nii-san?"
My younger sister clung to me playfully, her demeanor innocent and carefree. Yet, when no one else was watching, she took my hand and intertwined our fingers almost furtively, her slender, childlike fingers moving with an unexpectedly seductive grace.
This girl is really...
I inwardly smiled wryly.
She appeared straightforward, but her personality, attitude, and behavior all had hidden depths.
Ironically, I could feel a parental affection toward Marin that I never felt for my own parents.
"Come on, Nii-san, Nee-san!" Marin urged cheerfully.
"Look, even Marin-chan is telling you to get closer—Manaka, Ryosuke, stick together!"
"Ugh, I know! Stop rushing me!"
Manaka cautiously leaned closer, her shoulder brushing against Ryosuke's, who was being nudged by Marin.
"...Ugh."
"Nee-san."
Ryosuke kept the camera steady, whispering in a barely audible voice:
"Congratulations on graduation. Let's stay in touch..."
"... Yeah," Manaka replied, her voice fading away but her pronunciation clear.
"I'm taking the photo now."
Takuma pressed the button on his phone and snapped the shot. Ryosuke and Manaka smiled with a sibling-like closeness. From a spot neither their parents nor Takuma could see, their fingers remained intertwined.
*****
Read more than 1000 chapters worth of content over on Patreon! Patreon.com/IncognitoNovels