How Using My Oppai Skill to Enlarge My Sister’s Breasts Led to Building a Harem - Chapter 2

Chapter 2

My little sister Ai and I had fallen into a routine of daily sex.

Pann♡ Pann♡ Pann♡ Pann♡

“Ahn♪ Onii’s cock♡ It feels so good♡”

“Your pussy’s the best, Ai!!”

I gripped Ai’s plump, middle-schooler hips—impossibly full for someone still growing—and pounded my rock-hard cock into her from behind, panpan, in a standing position.

“Onii♡ I’m gonna come again♡”

Ai clung to the living room pillar, her legs trembling as she teetered on the edge of climax, her voice pleading.

“Go for it, come! Onii-chan’s got you!”

“Kuuu♪ Ahaa♡ It’s coming, something crazy’s coming~~~♡♡♡”

Pann♡ Pann♡ Pann♡ Pann♡ Bachun♡

“Ohhh♡ Haaaa♡ Aah♡♡♡”

Unable to hold on, Ai collapsed against the pillar, her body convulsing with orgasmic shudders, biku biku.

I hoisted her hips with both arms to keep her from falling, letting the swelling desire burst from the tip of my cock.

“Your cum♡ It’s coming out♡”

Even in her climax, Ai seemed thrilled by my twitching cock, flashing me a mischievous nishishi grin.

“Haaa, it’s out, it’s out.”

I muttered, pulling my condom-wrapped cock from her pussy with a chupon.

“Yup♪ You came a ton again♡”

Ai deftly slipped the condom off, brimming with cum, taputapu. She tied it off and dangled it proudly in front of me.

“What’s this, number five today?”

“Fifth one, look♪”

With some newfound knowledge from who-knows-where, Ai tied the cum-filled condom to the side of her panties and slipped them back on.

“Tada♪ I’m gonna milk you dry today, Onii!”

“Yeah, but I’m kinda beat. Let’s grab lunch.”

It’s summer break, so no school for either of us. Ai, the track team ace, had been skipping practice lately, claiming she’s under the weather—really, she’s hooked on sex with me.

“Hmm, true. Gotta fuel up to make more cum♪”

“Yep, we’re gonna keep going, so you rest up, Ai.”

I warmed up the lunch Okaa-san prepped this morning, setting the table for me and Ai.

(She’s gotten even cuter lately…)

She’s only a third-year middle schooler, but her bust is nearing triple digits. Yet those massive mounds don’t sag—they jut out, taut with youthful defiance.

“And your nipples are looking prettier too.”

“Ah, Onii’s staring at my oppai again!”

“Oh, sorry…”

“Just kidding♪ You can look whenever you want, Onii.”

She’s the perfect sister. Not just her body—her face is cuter than anyone’s, and her personality’s golden. She’s way too good for a guy like me.

Maybe because I was thinking that, my naked groin started to throb, guragura, with heat.

“Onii♡ You’re hard again?”

“That’s ‘cause you’re too cute, Ai.”

“Nishishi♪ Wanna do it while we eat lunch?”

Ai flashed a new condom with a grin.

“Guess I’ll have you feed me mouth-to-mouth again?”

“You really love me, don’t you♪”

Obviously. What brother could hate a sister this sexy and adorable?

“You’re the cutest in the world, Ai.”

“Nfufu♪ Hurry up and do me, Onii♡”

And so, we kept at it until our working parents came home. We’d eat dinner like nothing happened, then sneak more sex after they went to bed.

“Onii, you can’t go panpan so loud♡”

“But your pussy feels too good!”

I’d snuck into Ai’s room, climbing onto her bed. Under the covers, I draped myself over her youthful yet voluptuous body, thrusting my swollen cock in and out with reckless desire.

“Even if they’re asleep from work, this is… nnn♡ juzuzu♡ haaa…”

“You’re so cute, Ai!”

Pann♡ Pann♡ Pann♡ Pann♡

The covers muffled some of the sound, but my lust-driven hips didn’t care, slamming into her with wild abandon.

“Hiii♡ It’s too good, I can’t think straight♡”

“Haa haa haa, Ai! Ah, ah, ah!”

“Ahhh♡ I don’t care anymore♡ I’m coming~~~♡”

Ai’s voice rose into a sultry, feminine cry, loud enough to wake our parents. Hearing her sweet moans, I shot my load—byurubyuru♡—for the umpteenth time today.

“—Aaa… haa… it’s out. How many times was that?”

“Haaa♪ Thirteen, Onii. New record!”

We’d blown past a dozen rounds. Even the bulk condoms were running low. I knew this reckless sex spree would eventually crash and burn.

But even so, I couldn’t imagine giving up this sweet life with such an irresistible girl. Holding that contradiction in my heart, I slipped back to my room.

※

Satsuki’s Perspective

I’d finally mustered the courage to confess to the hot soccer club guy I’d been crushing on. My heart felt like it’d explode during that moment.

…

“Um… I’ve liked you for a long time, ××-kun…”

It was summer break, my third year of middle school. I’d arranged to meet him behind the school after his club practice, alone. That line I’d just said? I spent all night crafting it. It was plain, but it carried every ounce of my feelings.

“Yeah, I’ve always noticed you too, Satsuki. Let’s go out.”

He flashed me a dazzling smile. My heart went dokin, and I couldn’t help but stare at his handsome face. But something nagged at me.

(He’s totally staring at my chest…)

I’d done my research. ××-kun loves big boobs and rejects any girl with a flat chest. That’s why I let Ai’s brother see and rub my oppai to make them bigger. My dream came true—he accepted my confession. But something felt… off.

“I’m so happy, ××-kun…”

I said it, but my racing heart was starting to calm.

“Cool, wanna go on a date on the next club break?”

As he spoke, he casually slung an arm around my shoulder, pulling me close so my chest pressed against him.

“U-Uh, yeah… I’ll text you, okay?”

I could feel his sleazy gaze on my uniform’s curves, like he was checking if my boobs were real. That look scared me, and I started to pull away—

“Hey, let’s chat a bit more♪”

He grabbed my breast, pretending it was an accident.

“Kya!? Ow…”

“Oh, sorry, sorry. But it’s fine, right? We’re dating now.”

××-kun kneaded my oppai—bigger now thanks to Ai’s brother—guniguni♡, with no regard for me.

“Ow! Stop… stop it!”

His rough grip crushed my sensitive, still-growing breasts, sending sharp pain through me.

“It’s good, right? Feels nice, yeah?”

“No… it hurts! Stop it!”

The pain overwhelmed me. I shoved his arm away and ran. I’d been so excited coming here, but how did it turn out like this? With a heavy heart, I fled the school.

…

(Ugh… are all guys like that?)

Disillusioned with ××-kun, I headed home.

(Maybe I was better off with small boobs…)

Lost in gloomy thoughts, I walked the empty school route—summer break meant no other students around. Then—

“Oh, Ai’s brother.”

“Huh? Oh, Satsuki-chan… Been a while, huh?”

I bumped into Ai’s brother coming out of a convenience store.

“What’re you doing around here?”

“Uh? Just, y’know, coincidence.”

Ai’s house is in the opposite direction. Coming to a convenience store this far out seemed odd. Looking back, I was in a weird mood, pissed off from being manhandled by that jerk.

“What’d you buy? Something naughty? Lemme see!”

“Hey, wait?!”

I snatched the bag he tried to hide and peeked inside. Normally, I wouldn’t do this, but my hurt feelings had me acting reckless.

“Let’s see… Oh!”

“W-Wait! Don’t look, Satsuki-chan!”

It was a box of condoms.

“Oh… sorry…”

I was shocked. I thought he was just a nice, average guy—not the type to score. But he’s out here getting laid.

“Y-Yeah, you’re older, an adult and all…”

“Uh, yeah. Just… pretend you didn’t see, okay?”

He forgave my childish stunt.

(Come to think of it, he’s always been kind…)

I’d pegged him as a plain, ordinary guy. But suddenly, he seemed like a mature man. That grown-up patience? He never once treated me roughly like ××-kun.

The moment I realized that, he started to look… attractive.

“Hey, do you have some time right now?”

“Uh? Yeah, a little, I guess.”

“Then come with me.”

I led him to a nearby park, infamous for banning most kid activities. We faced each other behind the playground equipment, hidden from view.

“What’s up, coming to a place like this?”

“Um… I never thanked you for before and just stopped coming. I’m sorry.”

I apologized as sincerely as I could.

“Oh, that? Yeah, it surprised me, but I’m over it.”

“Really? Thank you.”

He really was mature. He laughed off my rudeness, and it felt like a weight lifted. Maybe that’s why I decided to ask.

“So, um… could you rub my chest again?”

“What? Your chest? Here?”

I nodded firmly, needing to know how different he was from that guy.

“Please, Onii-san.”

“Uh, okay… Here goes.”

His hands slid over my chest. My D-cup oppai, even over clothes, were plenty big enough to knead.

With practiced ease, he squeezed them softly—funyu—massaging gently.

“Haa♪ Nnn… haa♡”

“Does it hurt?”

“No, it’s… fine♡”

Each knead sent pleasant currents from my chest to my core, like he was stroking my nerves directly with perfect precision.

“I’ll stimulate the tips too.”

“Ah, wait… nnuuu~~~♡”

When he pinched my nipples—kyu♡—a jolt of pleasure shot from my oppai to the back of my head.

“Ahaa♡ This is… crazy♡ Auu…”

“You okay, Satsuki-chan?”

My knees shook from the pleasure, and I felt my panties dampen as slick juices seeped out, jiwari.

“I’m… fine, Onii-san.”

I slumped against him, breathing heavily, trying to calm the ecstasy.

(So good… nothing like that jerk…)

Each deep breath filled me with his masculine scent, making my head spin.

(I’m so turned on… I’m falling for him.)

Once I realized it, I couldn’t hold back.

“Onii-san, let’s have sex.”

I turned, lowering my soaked panties to my thighs. My lewd scent spread—muwari—and I heard him swallow hard, gokuri.

“But… are you sure about me, Satsuki-chan?”

“It has to be you.”

Yeah, boys my age aren’t even on my radar anymore. I want an adult relationship with him.

“Please, put it in quick♡”

I wiggled my hips, begging. He couldn’t resist either, tearing open the condom box and slipping one onto his swollen cock with practiced ease.

(It’s huge… that’s a man’s cock for sex.)

The pink condom stretched tight over his rock-hard, upturned shaft, so obscene it painted my mind pink.

“Ready, Satsuki-chan?”

“Yeah, come on, Onii-san.”

“You’re so wet… Alright…”

He rubbed his hot, hard cock against my pussy a few times before easing the tip into my entrance.

“Kuh… uuu… ahh…”

“It’s tight, Satsuki-chan.”

I’d heard first times hurt, and it felt like my pussy was being torn apart. Still, I could feel his forceful cock ripping through my hymen, buchibuchi, pushing deeper.

“Ugh… it hurts…”

“Satsuki-chan, is this… your first time?”

“Haha♪ Yup, you’re my first, Onii-san.”

“Really…?”

He seemed shocked a girl spreading her legs for him could be a virgin.

“I’ll make it gentle, okay?”

He slipped his hands under my top, unhooked my bra, and started kneading my oppai.

“Khaaan♡ That’s… so good♡”

The direct touch amplified the pleasure, my body trembling, addicted to the sensation.

“Your pussy’s so tight, Satsuki-chan.”

He started moving his hips slowly.

Pachun♡ Pachun♡ Paan♡ Paan♡ Paan♡

“Hiii♡ It’s too good, I’m going crazy♡”

I was being pounded from behind while he massaged my oppai. The overwhelming pleasure erased the pain of my first time, making my mind boil.

“No more pain? Does sex feel good?”

“Yesss, so good♡ My oppai, my pussy, it’s amazing♡”

“Good. I’d hate for your first time to just hurt. Here, here!”

Pann♡ Pann♡ Pann♡ Pann♡

The sound of flesh slapping echoed through the empty park.

(I’m having my first sex with an older guy who’s not even my boyfriend, outside♡)

The thrill of it drove me wilder.

“More♡ Thrust harder♡”

“Alright, here we go!”

Panpanpanpanpan! The lewd sounds rang out like something from a porn video. Each thrust made my core ache, kyunkyun.

“Ohhh♡ So good♡ Too erotic♡ I can’t… anymore…”

“Haa haa haa! I’m gonna come, Satsuki-chan!”

Sensing my limit, he sped up. My hips rocked like a boat on waves, climbing higher.

“Aah♡ I’m coming! Coming coming coming~~~♡♡♡”

“Kuaaaa!!”

Dochun♡ My pussy was struck deep, and Onii-san’s cock trembled, spurting something out with a byukubyuku.

My mind, blank with pleasure, savored the sensation, basking in blissful afterglow.

(A guy who’s good at sex is just… amazing…)

In my melted haze, I dreamed of what the future might hold with Onii-san.

※

I messed up…

Even though she came on to me, I had full-on sex with a girl other than Ai.

At first, I thought Satsuki-chan was just that kind of girl—loose with her chastity, offering a quick fling as some kind of consolation.

(I never would’ve guessed she was a virgin…)

Determined to make her first time painless, I went all out to make it feel good, only to get swallowed up by the pleasure myself.

As I wrestled with what to do, Satsuki-chan spoke up first.

“You’ve got a girlfriend, right, Onii-san?”

“Uh, yeah… kinda.”

Technically, it’s my sister, but we love each other, so she’s basically my girlfriend.

“Would it be bad if I stuck around?”

“Well, Satsuki-chan, you’re cute, but… it’s complicated…”

I didn’t know how to respond. I couldn’t just say, “Let’s not meet again,” after taking her virginity.

“Then, how about being my sex friend?”

“Sex… friend?”

Sex friend. Sefure. Is that… okay?

“Just hook up with me sometimes, that’s all.”

“Sometimes, huh? Alright… sure.”

This is cheating, isn’t it? I’m doing all that with my sister every day, and now I’ve slept with another girl.

But what’s done is done. Now I have to figure out how to keep Ai from finding out while keeping Satsuki-chan satisfied.

Carrying this massive secret, I headed home with a lighter step to where my sister waited.