How Using My Oppai Skill to Enlarge My Sister’s Breasts Led to Building a Harem - Chapter 21 Part 1

Chapter 21 Part 1

The main event. I was about to commit incest with my real sister in front of all my lovers.

“Onii… do you hate me now?”

“No way.”

Ai doesn’t enjoy being watched during our incest either. So I can’t hesitate here.

“Come, Onii♡”

Ai’s adorable face, her large, beautiful breasts, her dripping wet pussy—every part of her electrifies my desire.

“Ai…!”

The moment I resolved to throw everything away and embrace Ai, something exploded deep within me.

It surged through my body, converging on my groin.

(My balls and cock… they’re burning, boiling like crazy.)

An unprecedented lust drives my genitals wild.

Gu gu gu gu

“Ah♡ It got bigger, Onii.”

“Haa, haa… Ai, I don’t care if I lose everything.”

“Un, as long as I have Onii, I don’t need anything else.”

Our faces draw closer.

“Ai.”

“Onii.”

““I love you.””

Chu

A soft kiss. We confirm our feelings with our lips, becoming one.

Zuchu♡ Pan! Paan♡ Paan♡ Paan♡ Paan♡

“Fwa♡ Onii’s… amazing, reaching so deep♡”

“Inside Ai…! It’s incredible…!!”

Ai’s pussy is custom-made for me. A unique flesh hole that fits my cock perfectly—a genetic compatibility no technique or tightness can rival.

“How’s my pussy, Onii…♡”

“Gu… Perfect! A flesh-kin pussy made for my cock!”

As siblings sharing the same genes, it’s only natural.

Pachu♡ Pachu♡ Pachun♡

Each thrust against her vaginal walls sends overwhelming pleasure from my cock up my spine.

“Onii’s cock… fits mine perfectly, right♡ — Nn♡ Nn♡ Nnn♡”

“Ah, aaa…!”

Her cuteness and the pleasure burn my brain. Each thrust has her perfect pussy clinging to me, leaving no gap around my glans.

“Onii♡ My pussy’s tingling♡”

Nuchi♡ Nuchi♡ Nuchi♡

Her vagina tightens further, its folds wrapping around me.

Her pussy clings so tightly it feels heavy to move.

“Ai! That’s too good!”

“Hahe♡ My body… moves on its own♡”

Nuju♡ Nuju♡ Nuju♡ Nuju♡

Her vaginal hole writhes like it’s sucking my cock. No one could endure such a hole—

“I’m cumming, Ai…!”

“Aha♡ Pound me hard, Onii♡”

“U, ooo…!!”

Zuchu♡ Zuchu♡ Zuchu♡

“An♡ It’s pounding♡ Echoing in my womb♡”

“Ai! Ai! Ai!”

Technique’s gone from my mind. I rely on our physical compatibility, thrusting my cock wildly—the only thing I can do.

“Ah♡ An♡… Onii’s hitting… my good spots…♡”

“Ai! Ai! Rero, Juru! Jurururu… Fuu, fuu.”

“Nn♡ Juru, Churu♡ Onii♡♡♡”

Only Ai exists in my vision.

No—maybe only Ai and I exist in the world now. And I’m okay with that.

In our private world, I thrust my hips frantically to unite with my beloved girl.

Pan♡ Pan♡ Pan♡ Pan♡ Pan♡ —

“Agu♡ Onii♡ Too much♡ Nhi♡”

“Ai! Ai! I love you! Aaa!!!”

Papanpan♡♡ Dochu♡♡♡

My excitement threatens to burst my veins, my arousal peaking at cumming in my sister’s pussy.

(I want to cum! Inside my sister’s vagina! Cum hard!)

“Cum♡ Shoot your seishi, Onii♡♡♡”

“Ai! Ai! ~! —U!!”

Dobyu♡ Byu byu♡ Byurururu♡

“Auu♡ Hot♡ Your seishi’s coming…”

“Ohh! Feels so good… I’m dying… Aga…”

I cum with ferocious intensity, my life force draining.

Drooling, body arching, I focus all my functions on ejaculation. My male instincts fully engage, filling Ai’s womb instantly, excess semen shooting out like a water gun.

Byu byu♡ Byubyubyu♡♡♡

“Onii♡ Unu♡ So much seishi♡ It won’t stop♡”

“Ah, ah, gua!”

Doju♡ Zun♡ Zun♡ Zun♡

“Aa♡ Getting pounded in my good spot while you cum♡ Hyaan♡”

I keep cumming, hitting her portio, making her feel it. But it’s not just thrusting.

My “God Hand” ability, once limited to my hands, now extends to my whole body, including my penis—a weapon to please a woman’s hole.

“So good♡ Onii’s semen♡ Stuffing me full♡”

But this power rebounds, amplifying the woman’s pleasure back to me.

(Hot. Hot. HOT… My body’s boiling, blood surging.)

My cock and balls pulse wildly. As my penis releases semen, my balls rapidly produce more.

The pleasure’s too intense. Endless ejaculation hell dulls my brain.

My lower half takes control, vision turning red, reason—shattered.

“GuoooHHH!!!”

“Onii!? Kya!!”

Zudon♥♥♥

“Oh♡ Ohh♡ Oh oh♡ — Ohhhoo♡”

“Ai! Ai! Ai! GuoooHH!!”

“My pussy’s breaking♡”

“I love you! I love you! I love you most in the world!! OHHH!!”

Bajun! Baju♡ Baju♡ — Bajun♡♡♡

“Aa! Aa! Aa! Gua! Take it!!”

Dobyu!! — Dobu! Dopu! Byurururu♡ — Dojun♡ Dojun!!

“Ogoo♡ Ngii♡ Breaking♡ I’m breaking♡”

“Get pregnant!! Pregnant!! Bear my child, Ai!! Pregnant!!”

I’m a beast now, ravaging my blood-related sister, the girl I’ve loved since birth, driven by desire.

The onlookers watching our incest are gone from my mind.

“Really♡ I’ll get pregnant!? Ohhoo I’m cumming♡”

Byurururu♡ Dobyu! Dobyu!

“My sister Ai! You should bear your brother’s child!! Guoa!!”

Dobyurururu♡♡♡

My cock’s a semen pump, firing my balls’ rapid production into Ai’s womb.

“Ahe♡ So good♡ My head♡ My pussy♡ Broken♡♡♡”

Like me, Ai’s broken too.

Dojun! Dojun! Dojun! — Zuchun♡♡♡

“Ai! Ai! Ai! Ai! Ai!”

“Onii♡ Onii♡ Onii♡ Oniii♡♡♡”

““I love you!!♡””

We devour each other’s lips. Only we exist in this world, our obscene fluid-swapping sounds echoing.

“More, I’ll love you more!!”

“Nhi♡ Don’t pull out♡♡♡”

I pull my cock, zunyuri♡, from her tight pussy and aim my still-hard shaft at her lower hole.

“Your body is mine, Ai.”

“Haa, haa♡ Ngiii♡”

I begin violating her anal hole too.

…

“Oh♡ Cumming♡ Still cumming♡ Ahh, ahh, auu~~~♡♡♡”

How many hours passed? Driven by desire, I kept ravaging Ai. We’ve become one, mating with broken minds.

“How’s it feel, Ai? Love your Onii-chan?”

“Nhi♡ Love you, so much♡ I only need Onii♡”

“You’re mine forever, Ai. I’ll love you always.”

“I’m so happy, Onii♡”

I whisper love into her ear while thrusting into her ass.

In front of us, Satsuki-chan, Ayaka-san, Miyabi-san, Yukino, Nao, and Riria watch me violate my blood sister, filling every hole with thick, breeding semen.

“Haa♡ Onii’s mine♡”

“And you’re mine, Ai.”

They’re watching, but I don’t care. I’ve sworn eternal love to the world’s best girl.

For the finale, I’ll set off grand fireworks.

“Here I go, Ai.”

“Oh♡ Oh♡ OooHH~~~♡”

From behind, I lift Ai and ravage her ass hole, zubozubo♡.

“Cum, Ai!!”

“Ngihiii♡ Ouoohhh~~~♡♡♡”

Ai explodes with climax from our anal sex, reaching her limit.

“Ngii♡ Guhi♡ Cumming♡ Dying from cumming~~~♡♡ — Aaa…♡♡♡”

As I unleash my remaining semen, Ai’s eyes roll back. Her intestines are stuffed with my semen, excess bursting out like fireworks.

“Ahe♡ Ahee♡ Ehehe♡”

We siblings keep shooting white fireworks in front of my lovers.

※

I regain sanity hours later, waking after passing out, nearing night. With our parents due back, the women leave without much talk.

“Sorry for leaving the cleanup to you, Miyabi-san.”

“It’s a maid’s duty to serve her master.”

“Sorry, everyone, for… this.”

I feel awful for making them watch me with my sister after calling them here.

“I can’t beat Ai, huh…” (Satsuki)

“That was intense, Onii-chan.” (Nao)

“Uh, yeah.”

“…” (Yukino)

“Hawaa~…” (Ayaka)

They’re stunned, conversation stilted.

“I’ll drive everyone home,” Miyabi says calmly, her steely resolve reassuring.

“Please. It’s not safe for them to walk.”

“Understood, master.”

She smiles, bowing elegantly. Her normalcy comforts me, and I gaze at her beautiful face with respect and gratitude.

“Then, I’ll take my leave.”

Her eyebrow twitches slightly, but she briskly ushers the women to the car and leaves.

“Haa… I really messed up…”

I never imagined this would happen. My lower half scares me, but I’m captivated by that blazing desire, pleasure, and love.

“Well, no regrets.”

Having the best sex with Ai and swearing eternal love? Even if everyone dumps me, I’m fine.

With a sage-like calm, I head to Ai’s room, where she’s sleeping.

※

Epilogue

<Satsuki’s Perspective>

“Haa… I’m his girlfriend, but I don’t stand a chance…”

I sigh heavily.

“What’s wrong, Satsuki? Trouble with your boyfriend?” Mom, Mizuki, asks.

“Mom… Well, it’s… uh—”

Darling and Ai’s sex overwhelmed me. I’m convinced I’ll never beat Ai. I confide in Mom, a seasoned love expert.

“Hmm, he’s grown that much, huh?”

“Will I lose to the other girls too…?”

The women gathered were all top-tier beauties. I have no confidence I can be number one.

“Well, how about Mom teaches you a special trick?”

“What!? There’s such a thing?”

“Fufu, it’s—”

※

<Yukino’s Perspective>

“Yuki-nee!”

“Ah… Nao. What’s up?”

“What’s up with you? Walk properly, or it’s dangerous.”

Right, Miyabi-san, the Saionji maid, drove me home.

“Thanks, Nao…”

“You seem down.”

Of course. I’ve been with him for over half a year since starting school. Knowing he’s committing incest, a taboo, clashes with my admiration for their intense love.

“I get it, Yuki-nee. You wish you were the one he loved like that, right?”

“It’s… just to you, but—I was jealous.”

“Nishi, right?♪ Siblings loving each other against the world is amazing.”

Nao laughs, but I—

“You can win.”

“Huh?”

“Together, we can make Onii-chan lose control.”

My fading spirit sparks with hope from my sister.

“Together?”

“Yup, we’ll fight sibling bonds with sisterly bonds.”

“Right… That’s a good idea, Nao!”

※

<Ayaka’s Perspective>

“Fwaa~”

“Ayaka-ojousama.”

“Hawaa~”

“Ojousama, excuse me.”

“Kya!”

Miyabi presses a point near my chest, snapping me back to reality.

“Miyabi…”

“Don’t make that schoolgirl face, ojousama.”

“But…”

I didn’t know such a world existed. Literature portrays sibling love as platonic, but—

“I knew nothing about men and women…”

“It’s… not normal, to say the least.”

“But they truly love each other, right?”

“Undoubtedly.”

Could I intrude on their bond? The thought crosses my mind.

“Ojousama—no, Madame.”

“Y-Yes, Miyabi?”

Being called Madame recently grounds me as an adult.

“Love isn’t everything. To win a man, you need strategy.”

“Right… (Strategy?)”

“Your child grows in your womb.”

“…!? (Right, his first child… but)”

“It can’t be public, but no man ignores his child’s birth.”

“I see… (What does that mean?)”

“More time with your child deepens his affection.”

So, invite him to the estate often.

“Is there a way?”

“Of course. First—”

※

<Riria’s Perspective>

(I never thought he was that kind of guy.)

Having beastly sex with his blood sister, laughing—he’s the ultimate male.

“Call me a bitch? I’m nothing compared to him.”

He’s a pervert. The ultimate pervert, beyond me. A true deviant ruled by his lower half.

That’s why—

“I want him. That huge, insatiable cock, that crazed sex…”

He’s perfect for me.

“No other guy matters. I’ll make him mine.”

※

<Ai’s Perspective>

I have an older brother, kind, cool, and amazing at sex.

But that’s why he’s so popular.

I vaguely knew he was cheating with many women. I even feared he’d abandon me.

But that was baseless.

Onii-chan loves me most, swearing we’ll never part.

That’s why I need to better myself.

“Onii, I’m going to Shinkou Girls’ Academy.”

“Huh?”

It’s an elite school for refined girls. I never thought a commoner like me could enter, but…

“Miyabi-san, was it? That maid’s recommending me.”

“M-Miyabi-san…”

Onii’s shocked. Is she that impressive?

“But it’s a boarding school…?”

“…Yeah. So I won’t see you much…”

“Why… Do you hate me…?”

“No way.”

I love Onii most in the world.

“I want to become more feminine…”

Like Ayaka-san or Miyabi-san.

(The way Onii looked at them… it made me uneasy.)

“You’re already plenty cute, Ai.”

“That’s not enough. If I stay like this, someone else will take you…”

So I need to become the best woman.

…

“Nice view, huh, Onii?”

“Yeah.”

We were invited to the Saionji estate, dressed up by maids with pro-level makeup skills.

“You’re beautiful, Ai.”

“Thanks, Onii.”

His praise warms me, but it’s not enough. My skin’s tanned, hair short for convenience. My speech, manners, elegance—everything’s lacking.

I can’t match them.

That’s why I’ll leave Onii temporarily to become a woman he’ll brag about.

“So—wait for me, Onii♪”