How Using My Oppai Skill to Enlarge My Sister’s Breasts Led to Building a Harem - Chapter 8

Chapter 8

I was performing a massage on Saionji Ayaka, a woman referred by Yukino, to treat her breast cancer.

“Let’s start by protecting the area around the affected part. Please lie on your back.”

“Yes, sensei.”

Saionji-san seemed to trust me, following my instructions. Her breasts, previously pulled down by gravity while seated, now rose like mountains when she lay back.

(They don’t sag at all. Incredible firmness and density… so beautiful.)

I recalled the history of mountain worship in humanity, the belief that gods reside in high peaks. The mountains before me seemed to house a goddess.

Feeling reverent, I instinctively pressed my palms together. Opening the lid of the baby oil I’d prepared—

“It might feel a bit cold.”

—I poured the smooth oil over her breasts.

“Yes… nn, fuu.”

This oil, safe even for babies, doesn’t make skin too slippery or cause irritation when used properly. I kneaded her breasts from base to peak, gyu♡, to spread it evenly.

“Nn♡ Hia…!”

“Is it okay? Tell me if it hurts.”

“N-No, it’s fine… not painful at all.”

Cancer can spread through blood flow, so the entire breast needs care. Visualizing harmful cells, I pressed along the blood vessels.

Gunyu♡ Guni♡ Gunyugunyu♡ Guniii♡

“Aku…! Nn, nnn~~~♡… haan♡ Haa, haa…”

I repeated the process, cleansing the breast internally.

“Haa… haa… will this cure it?”

“Attacking only the main cause could let it spread through blood flow.”

“Yes.”

“So, we first boost immunity around it to expel foreign matter.”

Tracing the blood vessels from the tumor site, I helped her visualize their connection to the whole breast.

“I see, that makes sense.”

“We’ll need several sessions. Let’s improve it gradually.”

“Yes, sensei!”

And so, every day after school, I went to the clinic to treat Saionji-san’s breasts.

…

Gunyu♡ Guni♡ Gyuuu♡

“Nhaaa♡ Hiii…♡”

“Don’t hold back if it hurts, okay?”

“I-It’s fine…♡”

It was the fifth day of treatment. An hour daily had made us friendly enough for small talk. She was embarrassed about moaning loudly, but I explained it’s normal when stimulating sensitive nerves.

“—That’s why making sounds is good.”

“I thought… I shouldn’t make indecent noises.”

“Holding back raises blood pressure, which is worse.”

“Sorry…”

I’d suspected before, but Saionji-san seemed like a refined lady from a good family—her appearance, speech, and manners exuded elegance.

“The Saionji family is just an old, ordinary household.”

“Really? So it’s just you who’s especially beautiful?”

“N-No, I’m not beautiful…”

With her looks, hasn’t she heard that a million times? As I wondered, she said,

“My husband thinks I’m ugly.”

“Huh… what?”

(Such a beauty, ugly? What kind of taste does that guy have?)

“When I found out about the cancer, I told my husband…”

“He must’ve been devastated…”

“He said these big, tacky breasts should just be cut off.”

“W-What…?”

I was beyond angry—stunned. These divine breasts… cut off?

“Is he serious…?”

“My husband… likes small-breasted, young girls…”

“Even so, that’s insane…!”

Liking small breasts or young girls is fine, but blaspheming oppai is unforgivable. Why can’t he love both small and large breasts?

“I… I can’t forgive a guy like that…”

“Sensei…?”

“You’re beautiful, Ayaka-san. Your looks, your heart—everything’s wonderful.”

“T-That’s…”

“You’re a goddess, with breasts like a deity’s statue.”

“Oh… to be praised so much…”

I swear to the breast gods, I’m not lying. They see through my heart, but I’m certain her husband will face divine punishment.

“I’ll definitely heal your breasts, Ayaka-san. Be confident.”

“Thank you, sensei…!”

And so, we grew closer rapidly.

…

“The treatment’s going well. Any changes in your condition?”

“My body feels lighter lately. And the lump seems smaller…”

“We’re protecting the whole breast with daily pressure. At this rate, it could be cured.”

“R-Really…!?”

I felt progress. It took intense focus, but I was getting the knack for attacking malignant tumors. An hour of this was like tightrope walking—exhausting but effective. The tumor was shrinking.

“Let’s do it today!”

“Yes! Please, sensei♪”

Ayaka-san smiled at me, and my heart thumped loudly.

(What was that…? She’s married…)

No matter how awful her husband is, I wouldn’t steal another man’s wife. That’s not socially acceptable.

(Just my imagination…)

Convincing myself, I massaged her breasts, continuing treatment.

…

Half a month into treatment, the large tumor was barely detectable.

Munyun♥ Guniii♥ Purun♥

“How’s it feel, Ayaka-san?”

“Ahn♡ Hiii♡ I-I don’t feel it…♡♡♡”

For the finishing touch, I pressed acupoints to check for abnormalities.

“Here?”

“Ah! Yiiii~~~♡”

Her body jolted.

The acupoint I pressed, a nerve hub, was also an erogenous zone.

Even if it’s treatment, hearing a beauty like Ayaka-san moan wildly sent sweet shocks to my groin.

“All done. How’s it feel?”

“Ah, unu♡ Aaa…”

Pretending not to notice the wet sheet under her groin, I asked.

“Haa…♡ Haa…♡ It’s completely better.”

She confirmed, touching her breasts.

“The hospital?”

“Yesterday, the doctor was shocked—the cancer’s gone…”

“Then it’s fully cured.”

“It’s really… gone…”

Rubbing her breasts, munimuni, she looked emotional and oddly cute.

(No need to meet anymore…)

“Congratulations.”

“Thank you, sensei. I don’t know how to thank you…”

“No need. I’m just happy you’re happy.”

“Sensei…”

I suppressed my feelings, planning to send her off with a smile. Her keeping those beautiful breasts—that’s my happiness.

“Then why do you look so sad?”

“Huh…?”

I wasn’t… I shouldn’t be.

“Are you… feeling the same as me?”

“Ayaka-san?”

“Thinking we won’t meet again makes my heart ache.”

“Ah…”

Exactly. My heart’s been gripped with pain.

“I… I don’t want to stop seeing you…”

“Sensei… come closer.”

“Y-Yes.”

I approached, her face clear.

“Sensei, chu♡”

“Ah… this is…”

“I’ve fallen for you, sensei.”

“Ayaka-san…!”

Her soft lips and sweet feminine scent awakened my male instincts.

(She’s married, but… to hold such a beauty… I don’t care anymore!)

“Sensei… ahn♪”

Grabbing her shoulders on the exam table, I pushed her down and kissed her.

In the quiet clinic, wet smacking and slurping echoed.

“Sensei, juru♡ Kissing… chuzu… is so intense, jururu♡”

I was lost in the charm of this refined, ladylike woman.

“You’re too perfect, Ayaka-san. I know it’s wrong, but I can’t stop…”

“I don’t care about my husband anymore… I was ready to end my life if I lost my breasts.”

“What…!?”

She’d been that desperate.

“I thought no one understood me… but…”

“…”

“You got angry for me…”

That moment—her husband’s cruel words. I’d never been so furious.

“You saved my life, sensei. So I decided to live for you.”

“Ayaka-san… I’m just a student, powerless. I’m not sure I can make you happy…”

That’s my honest feeling. I’m just a kid playing doctor, with no confidence to protect her in the adult world.

“You can, sensei.”

“Huh?”

“You have these hands—surely a gift from God.”

She reverently rubbed my hands.

(Someone said that before…)

I don’t know what my hands are, but if it’s an innate ability, maybe it’s divine.

“I’ll create an environment for you to use your gift. So…”

“Ah…”

“Leave everything to me.”

Her hands slid over me, unbuttoning my shirt. Frozen like in a spell, I let her strip me.

“What a strong body…♡”

She was excited, like it was her first time seeing a man.

“You didn’t… with your husband?”

I shouldn’t ask, but it slipped out.

“He… couldn’t get aroused by me. Only obligatory baby-making…”

“Not aroused by such a beauty…?”

“He only likes… young girls.”

Why marry her then? I didn’t pry, keeping the tone light.

“Then I’m the only one who gets to see this cute Ayaka-san?”

“Fufu, yes, only you♪”

She pulled down my pants, leaving me in boxers.

Gulp… “Excuse me.”

With a breath, she slid off my last layer.

But her face was too close.

“Kya! W-What…?”

My cock slapped her face.

“You okay?”

“Y-Yes… oh, this is a penis… so big…”

Had she never seen one properly?

“Really?”

“My husband’s was half this… no, I shouldn’t compare.”

Love matters most, but he fails there too.

“Do you know what comes next?”

“Um… with my mouth?”

A blowjob? Maybe because her husband couldn’t get it up…

“Will you?”

“Of course♪ Nn… nnn!? Puha”

She tried but spat it out, struggling.

“Sorry! I couldn’t breathe…”

“It’s okay. Slowly, from the tip.”

“Yes…! Aamu♡ Jupu, ju… jururu♡”

She stopped forcing it down, sucking around the glans.

Chu♡ Jupu, jururu… zuzo♡ “It’s getting bigger…”

“Your wet tongue feels amazing.”

“Nfu♪ Haamu♡ Ju, juzuzu… rero♡”

Emboldened by praise, her tongue moved faster, more lewdly.

“Ah! That’s perfect… too good.”

Despite my restraint, she grabbed my hips, sucking halfway down with devotion.

Jubo♡ Jubo♡ Jurururu…!

“Ah, no… I’m coming!!”

Her dedication moved me, and heat surged from my core.

Dobiyu♡ Thick cum shot into her throat.

“Nn!? Gok… nfu…”

“Don’t force it, Ayaka-san… ahh, coming…”

“Nfuu… fuu… gok, nku♡”

Tears in her eyes, she swallowed my cum with effort. Her loving devotion was so beautiful, filling my chest with longing.

“You’re… truly wonderful…”

Nku♡ Nku♡… juru, chupo♡

I gently stroked her glossy black hair.

“Did I do well?”

“Absolutely. I thought you might be the most wonderful person in the world.”

“Fufu, exaggerating.”

No, I was in love with her in that moment.

(No, no. I have Ai, my beloved sister, and my fiancée…)

And she’s married. I can’t go further.

The thought weighed my heart like iron.

“Don’t make that face…”

“But we…”

“This is my thank you.”

“Ayaka-san…!”

Her words sealed my rationality. I’d only love the woman before me.

“Ahn♡ Come, sensei♡”

Boldly, she spread her pussy lips, exposing her entrance.

It was stunningly pink and pristine, despite her experience.

Seeing it, blood rushed to my cock, swelling it to its limit.

“I’m going in!”

“Ahn♡ Oh… big! Nuuu…!”

Her pussy was incredibly tight. No membrane, but it stretched like a virgin’s.

“This is… sex…! Ahh…♡”

“It’s in, Ayaka-san!”

“It’s stretching me… reaching the deepest part…♡”

It was her first time this deep; she lovingly stroked her belly where my cock reached.

“That’s your womb.”

I knocked on her cervix, konkon.

“Hyan♪ It’s tapping…!”

“And… here’s your sweet spot.”

With practiced moves, I probed her cervix, finding her portio.

“Ahn♪ How do you know…♡”

“I know everything about you.”

I’d mapped her breasts and pussy’s sensitive spots. Using all my knowledge, I targeted her.

Paan! Paan♡ Paan♡ Paan♡ Paan♡

“Hau♡ Ah, ah, ah…♡ Feels… good…”

I pressed further on her pleasure.

Munii♡ Gunyu, munyumunyu♡ Gyuuu♡♡♡

“Ahaa♡ Hii, my breasts… no…♡ I’m feeling it…”

I knew every erogenous zone of the breasts I healed. Tracing nerves from base to peak, I kneaded upward.

“First time here?”

For treatment, I’d avoided her nipples. Now, I teased them, kurikuri♡.

The effect was dramatic.

“Nhhiii! My breasts are tingling…♡”

Her loudest scream yet—her breast nerves, developed by me, linked directly to her nipples. Each tweak made her jolt like shocked.

Paan! Paan! Paan! Paan!… Paan♡♡♡

“No♡ My indecent voice… it’s coming out♡ Nnn…♡♡♡”

Kneading her breasts and thrusting, zubozubo, she burned with pleasure.

Gunyuu♡ Paan♡ Paan♡ Paan♡ Kyuu♡

“Ohh♡ No…♡ This voice… don’t listen…!”

Blushing, she tried to suppress her moans, but her body wouldn’t obey. Her pleas only sounded like beautiful music to me.

Pachun♡ Pachun♡ Pachun♡ Pan♡ Pan♡ Pan♡

“Let me hear more! Your sexy voice turns me on!”

“Noo, ahh♡ Oh, oh, ohh♡♡♡”

Her goddess-like face, messy with tears and drool, felt ecstasy.

Mischief sparked in me.

“Me or your husband… who’s better!?”

“Ah♡ Ah♡ Ah♡—I can’t say…♡”

“Ayaka-san! Not enough…!?”

Dochun♡ Dochun♡ Dochun♡

“Nhhiii♡ Aaa…♡ This… real sex… my first time…♡”

“I’m your first, huh?”

“Yes♡ My first…♡”

I didn’t take her physical virginity, but I claimed her heart’s first.

That realization unleashed the “man” in me.

“Ayaka! Ayaka! Ayaka! I love you…!”

Dochun♡ Dochun♡ Dochun♡ Dochun♡

“Oh♡ Ah♡ Ah~~~♡ I love you too… I love you…♡♡♡”

“I love you! I love you!”

Like true spouses, we made love—groping, slurping saliva, rubbing mucous membranes.

“Aaa, I’m… falling♡ Falling…♡”

“Fall! Fall! Fall! You’re mine!!”

Zupan! Zuchu♡ Zuchu♡ Zuchu♡ Dochun♡♡♡

“Yii♡ Aa…♡ I’m… coming, coming, coming♡ Coming~~~♡♡♡”

“Ahhaa~~~♡ It’s shooting… this is real sex…♡♡♡”

I came instinctively, no thought of protection. My creampie-trained cock pulsed, dokudoku, pumping thick seed.

Byuku♡ Byuku♡ Each pulse drove semen deeper.

“Ahn♪ Don’t grind my womb…♡”

“Sorry… got carried away…”

“Fufu♡”

Her words snapped me back to reality. We’d acted like a couple trying for a baby—something forbidden. But I’d already coated her womb.

As I pulled out, thick cum gushed, gopoo♡.

“Um, about protection…”

“It’s fine, don’t worry.”

“Phew… okay.”

Relieved or disappointed, we embraced, naked.

“Can we… meet again?”

“If you’re okay with it, I’ll come for more massages.”

“Yes! Please do!”

And so, we entered a secret relationship no one could know. What it would lead to, we didn’t yet understand.