The Isolated Sister
A few minutes of being carried along in Doctor's arms brought us to a halt before a thick iron door that, at a glance, could only belong to an isolation facility.
"There's a Witch in the lab… well, calling her that feels a little wrong. Let's just say I've got an acquaintance who's fallen to corruption."
A bitter look crossed her face, guilt and regret welling up behind it — then she glanced at the cure in her hand and muttered to herself, as if making a promise.
"It's fine. In the experiments, it gathered and expelled nothing but Black Mana, perfectly… it'll be fine. And even if it doesn't work, I've got this little guy…"
She held me tight as she muttered, a new side of Doctor I hadn't seen before — nervous, clinging. The person in isolation had to be someone precious to her.
This time, even if I had to step in, I would restrain my lust, take on the resolve of an OB-GYN, and handle this professionally—
Wait. Why was I automatically assuming this precious person was a woman?
What if it was a man?
GRAAAAH!!
I could feel the cuckold horns that didn't even exist roaring inside me. Doctor had already offered me her virginity and even agreed to get pregnant. If this person turned out to be a guy, I would knock Doctor up without a moment's rest and turn her into a tentacle factory…!
I kept spinning these useless thoughts long enough for her to undo lock after lock after lock, until at last the door opened.
And inside, lined up in endless rows, were dolls shaped like black-haired beauties so gorgeous it was downright unnerving.
AAAAAH—TENTACLEEE!!
I can't even play horror games, okay?! I'm a massive coward!!
Faces of terrifying beauty, yet utterly expressionless; pale skin with every ball-jointed articulation fully visible — and they were all naked…
Oh. You can see the nipples and pussies.
Suddenly, it wasn't scary anymore.
If they'd got tits and pussies attached, wasn't this just an onahole battalion? Ever since being reborn as a tentacle, I'd only been looking at Topaz, Doctor, and the Witch — women whose chests went past busty and straight into colossal — so even though these would have counted as big by my human-era standards, they somehow looked modest.
I'd thought they were terrifying a second ago. Now, faced with this many breasts and pussies lined up in formation… surely the Garden of Eden, flowing with milk and honey, must have looked something like this.
"You came again? How stubborn."
A dry, flavorless voice rang out. It was so barren of emotion that I could only imagine it as a high-quality text-to-speech reading from an AI that had never felt a thing in its life.
"…Is that any way to talk to your big sister?"
"It's because you're being stubborn in a way that doesn't suit an excellent older sister."
I turned from the dolls toward the voice. A woman who looked identical to them was refining an unfinished doll, still in the middle of making it. Even as they talked, she never so much as glanced at Doctor, her expressionless face showing not a shred of interest as she kept working.
Black hair and sharp eyes, similar to Doctor's. Unlike Doctor's irises, which called gold to mind, hers were a deep red reminiscent of blood. Where Doctor was messy and unkempt from her research, this woman was immaculate from her clothes on down — a clean white shirt and black skirt that evoked either a noble young lady or, given that pale skin, a vampire.
Thankfully, the fabric was thin enough that her black bra showed through.
Those plump, succulent nipples under that bra…
Having accidentally seen all those naked dolls, my OB-GYN resolve went straight out the window, and I started appraising her figure like some perverted breeding uncle.
Hah, no…! She's Doctor's little sister.
What's the word for your wife's younger sister again?
A pleasure to meet you, sister-in-law.
I stretched out a tentacle in greeting toward my sister-in-law… no, Doctor's little sister, who still wasn't looking our way.
"…I'm surprised. Even as I am now, I can still be startled."
"See? Bringing him was worth it."
Only then did she stop working on the doll and turn to face Doctor.
"What is this thing?"
"Ruby, this is a creature that can treat you."
"Did you get mind-controlled? That doesn't sound like you, sis."
The woman flicked her fingers through the empty air as if playing a piano, and with a faint rustle, the dolls that had stood still as the dead shifted into stances, poised to lunge at any moment.
"Wait! Hold on. Feel it — I bred this one so it wouldn't harbor Black Mana."
"…You're right. So? What could a mere monster possibly do that you'd go out of your way to bring it here?"
Brutal words, but at Doctor's intervention the dolls froze. Still, she didn't lower the hand wound with the threads that connected her to them, and the conversation continued in that murderous atmosphere.
Tentacle, CRITICAL CRISIS..!!
"This little guy is a monster, but because he has no Black Mana, his bodily fluids have the property of attracting it."
"I see."
A brief note of admiration, and only then did she lower her hand and continue.
"And with that, you intend to treat my corrupted state?"
"Yeah. I used his fluids to make a Black Mana inducer. If this works, that's the best outcome. If it fails…"
Doctor looked down at me with a slightly hesitant expression. The woman spoke as if she'd already predicted exactly that, her tone utterly casual.
"Is that so? Being a monster's broodmare once would be more efficient than staying like this, I suppose."
"…Will you be okay with that?"
"I can infer that my original self would have refused even if it killed me. But I think it's better than staying like this, continuously taking psychiatric stabilizers at near-lethal doses."
"It'll be fine. I ran the simulation a bunch of times, and in most cases the Black Mana expelled cleanly."
"You're talking an awful lot for you, sis. I take it I'm not one of those 'most cases.'"
"Ngh…"
Doctor looked like she'd been stabbed in a sore spot. Meanwhile, even though I knew I shouldn't, as a man I was filling up with anticipation at the prospect of exploring that expressionless woman's cave.
I was quite fond of the expressionless-girl-offering-up-her-body scenario. The kind where she let out the occasional moan and then got embarrassed was also good. Or the kind where she kept her deadpan all the way through, looking at the man determined to make her break and thinking he was cute on the inside — that was delicious too. Both flavors were so good I could hardly give either one up.
"A new medicine, after all this time."
"…I'm sorry."
"You don't need to apologize, sis. I was extremely mentally unstable at the time. If anything, I think you took the appropriate measures before my mind completely broke."
"Ruby…"
Doctor murmured her sister's name in a low, overflowing voice thick with mixed emotions, then drew from her clothes a pill that was a little too yellowish to quite be called white, and held it out to Ruby.
"Do I swallow it?"
"…Insert it into your vagina, like a suppository."
"…Today's full of astonishing things. It's been a while since I felt emotions."
Despite her words, she didn't seem to feel any shame whatsoever. She stripped off everything below the waist, spread her legs wide enough to give a clear view, and tried to shove the pill in.
At first it didn't go in easily, and Ruby prodded at her pussy as if masturbating. But as the pill gradually melted from her body heat, a dark yellowish lubricant-like fluid emerged, and she was able to push it in without resistance.
"I pushed it in as far as my fingers would go."
"Haa~ Fingers alone aren't going to cut it after all…?"
Doctor sighed with a conflicted look, glancing between me and her own clothes, then seemed to make up her mind. She pulled a long, extremely thick dildo from her clothes and approached Ruby.
What.
"It has to be shoved all the way to the womb…"
"Is that so? Here."
Even with her older sister about to ram something into her pussy, Ruby showed not a flicker of reaction. She spread herself open to make the insertion easier, like a patient receiving a medical exam, and parted her legs even wider.
Sister yuri play?! What the hell is this?! This is some once-in-a-lifetime shit…!!
Honestly, I could have pushed it in better myself. But the sight of Doctor's conflicted face and Ruby spreading her pussy with that vacant, expressionless look was a delicacy in its own right, so I decided to sit back in a front-row seat and enjoy the show.
Crrk.
"Nnh, that stings a little."
"Ha, fuck. Did I just take my little sister's virginity…? Treatment or not."
Mucus melted from the medicine, along with a faint trace of blood.
I wanted to have a rich debate over whether losing your virginity to a dildo made you a non-virgin or still a virgin, but sadly there were no gentlemen present to discuss it with. Personally, I thought the real kick was this: a slutty virgin bitch so horny she went and bought a dildo to masturbate with finally hooks up with the protagonist, then gets teary-eyed when no virgin blood comes out, confesses she used a dildo on herself, drowning in self-loathing and terrified he won't believe her.
"…! The Black Mana."
For the first time, Ruby's face showed something like surprise. Even as the Black Mana gathered, Doctor stared at a holographic panel with a somewhat conflicted expression.
"As I thought, it's not enough."
"Hnh."
Checking the numbers on the holographic panel, Doctor shoved a second pill into Ruby with a slightly impatient air. The medicine fizzed and bubbled as if it were some kind of effervescent tablet, and lubricant began to drool out in streams. And unless I was imagining it, Ruby's belly had puffed out a little too.
"This 'sexual sensation' thing isn't bad."
"Don't do things you'll regret when you come back to your senses, and keep quiet."
"That's a meaningless thing to say, considering you already shoved something into my genitals, sis."
Doctor, apparently out of comebacks, quietly shifted her gaze to the holographic panel.
"Tsk. Building a tolerance already, is it…"
"Tolerance?"
"I don't know if 'tolerance' is the right word. Think of the Black Mana as a fish. It's like it's gotten used to the fake lure, so it's not biting anymore."
"In that case, I'll have to receive that monster's seed directly, won't I?"
Ruby looked at me, her face still expressionless. But unlike that unchanging expression, it wasn't my imagination — her belly had definitely puffed out ♥, swollen as if she were pregnant, or almost.
"Before that, we expel the Black Mana the medicine already gathered."
"How? Going to suck it out with a vacuum cleaner?"
"No. It'll come out on its own."
"You mean it'll flow out?"
"No. It'll come out like… laying eggs."
"The medicine hasn't worn off, has it?"
Uhyooo~ Beautiful girl oviposition scene, GET~★
There wasn't a major change in that expressionless face, but the corners of her eyes were trembling, ever so slightly. She didn't say anything more, but she glanced at me once with a look that said it would have been better to leave this to me from the start, then shook her head as if deciding otherwise — and that somehow pissed me off.
Once the egg-laying's over, you'd better be ready…
I'd been planning to professionally dump a metric fuckton of semen with the mindset of an OB-GYN, but forget that.
I was cranking the sensitivity to 500x and shattering that deadpan…!