The Story of How Producing My Timid Older Sister Developed My Sexual Preferences

Chapter 017: Signs of Metamorphosis

After finishing shopping with my friends, I arrived home exactly at the time I told Sis I would return.

The nice smell of miso soup was coming from the kitchen, so she was probably there.

“I’m home~”

“Welcome back…”

Sis, standing in the kitchen, greeted me while awkwardly twisting her body and keeping her face turned away.

What’s with that movement? I thought, but then it hit me — makeup! I had been so preoccupied with Reina-san’s photo, the reverse pick-up, and imagining Sis in short pants that I completely forgot about the makeup. Shit, I’m really curious now.

“Sis, when you greet someone you have to look them in the eyes. I’m home.”

“Welcome back…”

Her face didn’t move even one millimeter.

“The longer you wait, the higher the hurdle gets, you know?”

“……”

“Come on, hurry up.”

When I closed the distance, she finally gave in and slowly turned toward me, looking up at my face.

“…………”

I was truly speechless. I had recently noticed she had a beautiful face, but this was on another level. Was the change from makeup really this dramatic, or did it just seem that way because it was my first time seeing it?

Her plump lips were coated in a light pink gloss, looking moist and inviting. The heart shape was emphasized even more seductively.

Her high nose had slightly less roundness, becoming more defined and giving her an even stronger exotic, sensual allure.

Her eyes had a light beige eyeshadow layered on them. The deep double eyelids were emphasized, giving her a more artistic and captivating look. Brown eyeliner made her eyes appear larger. They had such a strong pull that it was hard to look away.

The biggest change was probably her eyebrows. What used to be fluffy and completely unmaintained brows were now neatly shaped into a natural, elegant line. They rose sharply toward the arch to balance her droopy eyes, then gently tapered down toward the tail.

Looking at her whole face again, she could almost pass for a foreigner, but her eye sockets weren’t too deep and her eyes and brows were slightly spaced apart, which gave her a distinctly Japanese charm. That exquisite balance created a face that was uniquely hers.

Beautiful. Stunning. It was the truth, so I should have been able to say it immediately, but the words got stuck in my throat.

As I stayed silent, Sis’s expression gradually turned anxious.

This feeling must be what it’s like to be unable to confess to a woman you fell in love with at first sight. I realized I was so embarrassed that I couldn’t speak.

I had to say something… Sis looked like she was about to cry……

“…I knew my eyes weren’t wrong ahhhhhhhhhhhhhhhhh!!!!!!!”

Sis, who received my deafening shout at point-blank range, squeezed her eyes shut and covered her ears.

SLAM!

“Shut uuuuuup!!!! You damn monkey!!!!!”

Mom burst into the dining room after hearing my stupidly loud yell, calling me a monkey and kicking me in the thigh with a satisfying smack.

“Ouch!! Thank you! Thank you so much, Mom! For making Sis this beautiful!”

“You’re disgusting… She was already beautiful from the start.”

“No, seriously… This is the first time I’ve ever thought Mom was amazing… First time.”

“………… Let’s eat, Tabasa. I’ll help too.”

After giving me a look like she was staring at vermin, Mom stuck to Sis like glue.

I got that same look this morning too… When thinking about how to survive in this household going forward, it seems I should help out more.

While wiping the table with disinfectant wipes, I watched the two of them from behind.

Sis frying something, and Mom — who was a head shorter — chopping cabbage beside her. They were chatting happily, looking almost like sisters. I didn’t know… So they always talk like this.

From around my second year of middle school, I was unstable due to various reasons and was too busy dealing with myself to pay any attention to my family. In fact, I avoided them. I think it was because I hated getting nagged by Mom when my heart felt like it was about to burst. But after entering high school, I stabilized. I caused trouble for everyone by suddenly changing my target school at the last minute, but I believe it was the right choice.

“Thank you for wiping the table…”

“N-no problem, it’s nothing.”

When Sis brought over my oyster fry, her still-unfamiliar made-up face made my voice crack a little.

“Ah, I can serve my own rice.”

“It’s fine… Just sit.”

When I tried to stand up with my bowl, she took it from me.

“Come on, you shouldn’t spoil him so much, Tabasa.”

“I-it’s fine…”

“…………”

What the hell is that look for? This time it wasn’t even my fault.

We all sat down and put our hands together. I glanced at Sis, but quickly looked away. I’m getting nervous… even though it’s my own sister. I’ll try not to think about it too much right now.

Today’s food was insanely delicious again. This tartar sauce is drinkable.

My chopsticks wouldn’t stop moving. The food on my plate disappeared rapidly.

“Hey you, can’t you eat with a little more gratitude?”

Annoying old hag, I thought, but I temporarily put down my chopsticks. When I looked at the two of them, they had barely made any progress. More importantly… Sis really is ridiculously beautiful. Maybe it’s because she has exactly the type of face I like. At this level, I’m starting to wonder what other people would think.

“You’re too grateful, my hands won’t stop. But seriously, Sis, you’re amazing. You could become an idol or celebrity. Easily.”

“………”

Her mouth, which had been moving steadily, suddenly stopped. Her face slowly turned pink, and the blush seemed to fade.

“There’s no way. That world isn’t just about looks — it’s all about mental strength. Someone like Tabasa would collapse from exhaustion in two days.”

“Is it really that bad? But her appearance is perfect.”

At my comment, Sis’s chopsticks stopped moving entirely. I said her appearance was perfect, but her hair was voluminous and a bit frizzy. Her face is so strong that it actually makes her look like a stylish, unique beauty, but…

“Even those quiet, pure-looking girls you see on TV become ruthless demons who will do anything to step on others once you peel back a layer. I saw one with a face like a vengeful spirit in the elevator the other day.”

“I-I see…”

Mom, who works in an industry close to entertainment, probably wasn’t exaggerating.

“Besides, with Tabasa’s body, she’d definitely be forced to undress immediately. I guarantee it.”

At Mom’s words, Sis shrank into herself.

I wonder what it feels like to have a gravure idol as a sister… It might not be so bad, but it also sounds a bit unpleasant.

While the person in question was left out of the conversation, Mom and I talked about Sis’s beauty as we ate. Time passed in the blink of an eye.

“It’s fine, Tabasa. I’ll wash the dishes.”

“I’m okay, I’ll do it too.”

“Ah, I’ll do it.”

“…………”

“Oh, really? Then I’ll leave it to you. Let’s go, Tabasa.”

Mom quickly left the dining room and headed to the living room. Since it was better than having her hovering nearby, I didn’t complain.

“…It’s fine, I’ll do it.”

“No, I’ll do it.”

“I want to do it…”

“When I’m home, I’ll do the dishes every day from now on.”

“…Why?”

“That’s… wait a second.”

“……?”

I went to the entrance, took out the hand cream from the shopping bag I had left there, and handed it to Sis.

“This is for you. Your hands are a bit rough lately, so… since you’re going to become even more beautiful, I thought your hands should be pretty too…”

“…I’m so happy.”

Her beautiful hands accepted the hand cream and pressed it tightly against her soft chest. Tears began dripping onto it.

This reaction was completely different from what I expected, and it startled me. I thought she would smile shyly with that incredibly beautiful face.

“Y-you’re crying that much!?”

“Sniff… I’m just so happy… sniff… I can’t stop…”

“H-hey, don’t go to Mom like that! Sit here!”

I had no idea what to say. It was awkward, but if Mom saw her like this it would be bad. I’d definitely get beaten this time.

While listening to Sis’s sobbing behind me, I finished washing the dishes.

I never expected her to cry…

“Have you calmed down?”

“Sniff… yeah… sniff”

“Ah… your makeup is ruined…”

“I’ll go wash it off… and take a bath…”

“Yeah, do that. Also, do you have time after Mom goes to sleep?”

“…Yeah.”

Sis nodded and left the dining room.

Seeing her that happy made me genuinely glad I gave it to her—— but at the same time, I was now intensely regretting the terrible timing.

After making her cry tears of pure joy, giving her the extremely perverted loungewear I bought feels incredibly difficult.

I have no idea what kind of face I should make when I give it to her. If I grin stupidly and say “H-here, try this on. Hehe, it’ll look good on you, Sis,” the gap from earlier might actually make her hate me.

But I worked hard all day today just to see Sis wearing this. I’m definitely making her wear it.

With that determination, I decided to recharge in my room until the right moment arrived, carefully examining my treasure photo of Reina-san’s thighs like I was searching for her pores.

Chapter 018: Exposed Monkey

“God fucking damn iiiiiit!!!”

I pulled the blanket over my head, buried my face in the pillow, and screamed.

After stopping myself from zooming in on Reina-san’s photo, I took a bath, came back to my room, and saw a message from the older woman who had hit on me.

While remembering that mysterious age-unknown miniskirt lady, I was grinning like an idiot, wondering if she was a slutty college girl or a bitchy high schooler, and exchanged messages with her.

Her username was “Kaede♡” and her icon was a sparkly filtered two-shot photo with a young-looking girl.

At that point, my internal warning alarms were blaring, but I thought it was a glitch and turned them off.

We kept using polite language with each other while sending cute stamps, having a boring conversation—until…

・You don’t have to use polite language♡

・Really? I thought you were older. Are we the same age? I’m 16 this year.

・Ehh~ I’m so happy♡ I’m 12 and in first year of middle school! Is that no good?

The moment I read that, I threw my phone and dove under the blanket.

There’s no way a 12-year-old could be that polished. I wanted to believe it was some kind of mistake, but the way she wrote made it clear it was the truth.

If she was at least one year older it would’ve still been on the safe line, but until very recently, elementary schoolers were completely off-limits.

I wanted to at least pay the wombats dancing in my head minimum wage.

I thought I was definitely going to get laid this summer break. I even bragged about it to my friends… This is so embarrassing. I’m never telling them about this punchline.

So I got all excited because a 12-year-old reverse-hit on me…

“I want to delete this… from my memory…”

No. I’m the kind of guy who doesn’t stay down even after falling. Next time I’ll turn this embarrassing story into a funny anecdote and tell Reina-san. I’m sure she’ll laugh.

A kind older woman who’s good at listening is the best. I feel like I finally understand why old men want to go to cabaret clubs.

Thanks to fantasizing about happily chatting with Reina-san, I recovered a bit of my spirit.

I picked up the phone I had thrown earlier, sent Kaede-chan a harmless reply, and wrote: ‘I have to wake up early tomorrow so I’m going to sleep. I’ll message you again later.’ I probably won’t contact her again.

Then 10 PM arrived. Mom should’ve gone to bed already since she wakes up early. Yeah, I can’t let this day end with loli from start to finish.

I grabbed the shopping bag with the goods and headed to the living room.

As expected, only my sister was there. The moment I entered, she started fidgeting.

“Did Mom go to sleep?”

“…Yeah.”

In her hands was the hand cream I gave her. She must’ve used it. A faint scent drifted over.

“You used it.”

“Yeah… It smells really nice.”

I sat next to her and got straight to the point.

“Good. So… I bought you some loungewear. Will you wear it?”

“Yeah… Thank you… so much.”

She showed a genuinely happy smile and hugged the hand cream lovingly. She looked like a kid on Christmas morning.

This is getting dangerously tense.

I might have told her “shorts” this morning, but these are short pants. The length is completely different.

“You’ll definitely wear them…?”

“…? …Yeah.”

Don’t look at me with such pure eyes… If I give her these, will she think I’m a perverted bastard who looks at her sexually? …Come to think of it, I already called her body fucking lewd to her face before.

“Here, a present.”

I calmed myself down and handed her the bag.

With an expression of shy happiness, my sister pulled out the short pants.

“…!? T-These are way too small!”

Of course she’d react like that. But I’m making her wear them no matter what. I hold grudges. I haven’t forgotten about the sheet-sucking incident this morning.

“No, it’s fine. It’s an S size, it’ll fit.”

“Mm… No way, these definitely won’t fit…”

“They will!”

“They absolutely won’t!”

“You said you’d wear them!”

“Uu… No way…”

I flinched at my teary-eyed sister, but this is revenge, so I’m not in the wrong. It’s her fault.

Besides, I already know how to handle my sister when she’s in her refusal phase.

“I went through a lot of trouble thinking about you, choosing these…”

“…Uu.”

“Fine. I’ll give them to someone else. Hand them back?”

“…”

“Give them back.”

“…Nooo.”

“You’re not wearing them, right?”

“…Uu… You won’t laugh?”

“I won’t laugh. I bought them because I wanted to see you in them.”

“…Then I’ll wear them.”

Surprisingly easy. I thought she’d resist more. She took the short pants and disappeared toward the dining area.

My chest swelled with expectation. That final treasure I saw that night… I’ve finally reached it.

From the open dining room door, only my sister’s bright pink face peeked out.

“………”

“Huh? Couldn’t put them on?”

“…They fit.”

“See? Hurry up and show me.”

“They’re too short…”

“They’re short pants, obviously.”

“…”

From here it’s a battle of endurance. I’m not saying another word until she comes out. That face won’t work on me. I stare at her intently.

……No way, she still hasn’t come out. It’s already been three minutes.

“Haa… Maybe I should just go to sleep.”

“!? …!”

After letting her gaze wander for a while, my sister squeezed her eyes shut and finally stepped out.

My eyes were glued to her legs as she came out shyly with slightly pigeon-toed steps.

…What insanely erotic legs.

My heart raced. They looked pure white and plump like marshmallows, yet firm and tightly packed with meat like glossy white sausages. They gradually tapered down, and below the knees they were shockingly long. …I want a closer look.

“…Come closer.”

“Uu…”

She approached while rubbing her thighs together with almost no gap. I was so focused on her legs that I only just noticed — I couldn’t see the short pants.

She was pulling down the T-shirt I gave her to hide them. Hmm? They shouldn’t be short enough for the shirt to cover them…

“The shirt’s gonna stretch.”

“…I don’t want to.”

Even as she said that, her face grew even redder as she let go of the hem.

“…!? …So erotic.”

“Uuuu~~~!!!”

Way too erotic. It slipped out of my mouth. The hem was digging into her thick, juicy thighs, and the navy short pants looked like they were screaming.

In Reina-san’s photos I zoomed in on, there was plenty of room at the hem and they were longer. But when my sister wears them, they look like a completely different item — like the cashier swapped them. …These are basically hot pants now.

Right in front of me was something that looked like a volleyball uniform.

Shit, I’m getting hard. But I still haven’t seen enough.

I sat down cross-legged like my sister usually does, tried to look as calm as possible, and gave another order.

“Is the waist tight? Lift your shirt a bit.”

“N-Noo…”

Even while refusing, the shirt rolled up. The waistband was stretched to its limit, perfectly hugging her narrow waist.

Her words and actions no longer matched. Seeing her teary-eyed and completely obedient to me filled me with abnormal excitement.

I was fully erect, about to tear through my pants.

“…What about the back?”

“Uu… My butt… is showing…”

Like a puppet, my sister slowly twisted her waist. The full view gradually came into sight.

I understood from the side. Her ridiculously thick ass — impossible for a pure Japanese girl — was making the pants even shorter.

And this was my first time seeing her huge ass from the front. An absurdly angled inverted heart-shaped butt stretched the navy fabric to its breaking point. The overflowing lower part of her ass cheeks cast shadows on her thighs.

I can really see under her ass…

It wasn’t just hanging — it was being squeezed out by the pants, looking soft and plump.

“…Don’t look…”

“…”

As ordered, her hands were still holding the lifted shirt, so even if she wanted to hide, she couldn’t. She kept rubbing her thighs together shyly.

“I don’t like this…”

“…”

I was rock hard to the point it hurt.

While her back was turned, I changed my posture. I sat cross-legged and angled my cock to the left. The head was poking out from the pocket area of my pants, but I gently covered it with my hand.

“I don’t like this… Say something…”

Thump! Thump!

“…It’s the best.”

She seemed anxious from my silence and stomped her thick, juicy legs twice.

All I could think while watching her huge ass jiggle was that stupid, uncreative impression.

“Hey… Can I stop now?”

“No.”

“Uu, nnn~~!!”

Should I just jerk off right here…? N-No, am I a monkey?

I used to think only perverts grope girls on trains, but right now I desperately want to grab the mass of flesh in front of me. I want to rub against it and cum all over that huge ass and those white legs. My fantasies kept swelling.

I slipped my hand into my pocket and touched myself just a little. Just a little.

I could feel the precum soaking through. When I pinched the head, pleasure far stronger than normal masturbation shot through me.

How good would it feel to knead that ass, run my hands over those thighs… and what kind of voice would she make…? Shit, my hand won’t stop… It’s fine… Just a little, I’ll just relieve the ache a bit…

“Uu… Please… Forgive me already…”

“…Uu…!”

I couldn’t look away from her writhing hips. The area between her ass and thighs was faintly pink.

The voice from my fantasy and reality started syncing up…

In my head, I was already sandwiching my cock between her thick thighs from behind and slamming my hips against her.

My fingers stroking the head wouldn’t stop.

I couldn’t hold back anymore. It hurts. I don’t care what happens after this. I just want to surrender to my desire.

Ah, shit, I can’t hold it…

“Mou… No more… Teru-kun…”

“Kuh…!? Face forward!! Uuu…!”

Spurt!!!

Her voice, which now sounded like nothing but moaning, perfectly matched the image in my head.

My brain went numb. Even with weak stimulation, I easily erupted.

I almost rolled my eyes back, but when I saw her trying to turn around, I shouted on instinct. She flinched and quickly faced forward again.

“Uu… I’m sorry.”

“…S-Sorry, sis… I’m not mad. It was… way better than I imagined… You can change now. Thank you.”

“…Okay.”

She pressed down on her exposed ass and quickly left the living room.

My head gradually cleared as I came back to reality.

For some reason, my sensitive cock still wouldn’t go soft.

Now what?

Chapter 019: The Sage’s Resolution

It felt so good that my hips gave out — I couldn’t move.

Whenever I tried, my hypersensitive glans would rub against my shorts and my whole body would twitch. The inside of my pocket was so soaked with cum that it felt like it might start dripping if I walked. I couldn’t even pull my left hand out.

But I had no choice but to leave this place somehow. I steeled myself and tried to stand up, but my sister came back with a bright red face, now in her usual clothes.

Shit…

She can’t see this thing while it’s still rock hard. I sat back down and decided to wait until it shrank.

“Uu… That was so embarrassing…”

She plopped down on the sofa about a meter away from me. Her massive ass made the cushion bounce heavily.

“No, it looked insanely good on you. But yeah… the S size really was too small, huh?”

“I told you so!”

I didn’t expect her to be hiding that much. My sister’s dream of going to Australia probably won’t come true anymore… She’d get stopped at airport security. It’s way too dangerous.

“Haha… I’ll buy L size next time.”

“It’s fine, I’ll buy them myself…”

“Then let’s go together when I buy glasses.”

“…Okay.”

“Right, I should return these and exchange them for a different size. The tags are still on.”

“…No.”

“Why not? It’s a waste if you don’t wear them.”

“……”

“I’ll return them next time and get you a bigger size as a present.”

“……I’ll wear them.”

Of course I’m happy she wants to wear them since that’s why I bought them, but if she walks around in them, I really might lose my mind. I realized that painfully clearly after seeing her earlier.

Ah… I shouldn’t have remembered.

“No, you don’t have to force yourself. You were really embarrassed, right?”

“I-If Mom’s not home… then it’s okay…”

…That honestly turns me on even more.

But if I tell her not to wear them anymore, I feel like it’ll hurt her. Plus, I need to deal with this situation quickly. I’m at my limit — I can already smell it.

“Alright, alright. I’m glad you liked both the hand cream and the short pants. We both have school tomorrow, so shall we get some sleep soon?”

“…Yeah.”

“Good night.”

“…Night.”

“…”

“…Wanna drink coffee?”

“…No, I won’t be able to sleep.”

“…R-Right.”

“…”

Hey, when are you going to leave? I started getting anxious as my sister showed no sign of moving. The smell of my semen was starting to overpower the hand cream scent.

“I worked up a sweat, so I’m gonna take a shower. I’ll turn off all the lights, so don’t worry.”

“…Then I’ll wait.”

—Huh?

I had no idea what was making her act like this, but her stubborn refusal to go to bed was starting to irritate me.

Just go to sleep already!

“…Go to bed soon.”

“…Okay. …? It smells like the pool again.”

Busted.

“…It doesn’t.”

“…It does… This is the smell of bleach…”

“…”

“Wait… It’s coming from you, Teru-kun…”

She sniffed and scooted closer, closing the distance. The scent of her hand cream and her large, softly swaying breasts grew stronger.

“I said it doesn’t!!”

“!? W-Why are you getting mad…?”

“I’m not mad!!!”

“Uu… Lately we’ve been getting along so well… and suddenly you’re being cold… It’s because I’m fat after all…”

This sister of mine is seriously troublesome.

Though I admit my tone might have been too cold because I was panicking. It’s not like I’m some scumbag who thinks “I already came, so I’m done” after pillow talk.

My dick had finally started to shrink. My mind felt clearer than usual.

I could speak gently now…

“Sorry. I wasn’t being cold. You’re not fat at all — that’s ridiculous. I was just stunned because you looked way too sexy. I’m really happy we’ve been getting along lately too. I was imagining how beautiful you’ll become and went looking for clothes that would suit you. They really looked great on you. Sorry for making you anxious. I’m going to take a shower now. You can wait or go to sleep, but please don’t come into the bathroom until tomorrow morning. Got it? Answer with ‘got it’ or ‘I don’t get it’ if possible.”

“…Got it.”

“Alright, I’m off to shower.”

With my left hand still stuck in my pocket, I headed to the bathroom. I prayed my sister wouldn’t search “chlorine smell similar to chestnut flowers” on her phone.

I took off only my top and showered. I was too lazy to do anything else. I should’ve just washed everything in the bath.

“Man… I really did it.”

I didn’t plan on jerking off, but I couldn’t resist. I already knew I was weak to temptation and honest with my desires. It’s not just sexual desire — I’m the same with food and sleep. If there’s delicious food, I can’t stop until I’m full. If I’m sleepy, I’ll fall asleep even while moving and end up late.

I saw my sister right there and still came. I’m sick.

I never understood sex offenders before, but now I’m starting to worry I might become one someday.

“Aaah, I’m depressed.”

It might sound like an excuse, but it’s that body’s fault. I can confidently say I’ll never see a body more arousing than that again. That body drives people insane. Anyone would react the same way.

I managed to calm her down earlier, but maybe I should properly tell her not to wear them.

I definitely won’t be able to control myself. Like she said, we’ve finally become close siblings after so long. It’s wrong for me to look at her with such sexual eyes in the first place. I feel like I’m about to ruin everything.

After washing my underwear and shorts in the bath and throwing them in the washing machine, I returned to the lit living room.

My sister was sitting in her usual triangle position. On the table was her special homemade lemonade.

Watching the bubbles fizz, I felt an indescribable sense of emptiness.

Today was a pathetic day of being ruled by lust.

I’ll say it properly. I don’t want to look at my sister that way anymore.

“Thanks, Sis.”

“Yeah…”

“About those short pants earlier… You can keep them, but they were a bit too sexy after all. Maybe it’s better if you don’t wear them…”

My sister made a puzzled face. I knew she’d react like that.

“…Did they look weird after all?”

“They didn’t look weird. They really suited you. But how do I put it…”

I tried to tell her it was better not to wear them. But I couldn’t find the right words that wouldn’t hurt her or reveal my true intentions.

“…?”

“Sorry for saying confusing stuff. Oh right, the day after tomorrow we’re going to the beauty salon. Should be fun.”

“…Yeah, I’m looking forward to it.”

“I wonder if you’ll become super popular at school.”

“…That won’t happen.”

“I might get jealous. If you get a boyfriend, I probably won’t get to eat your delicious food every day anymore.”

“…That… won’t… happen.”

“…Huh?”

“Things like that won’t happen.”

I was about to say “You don’t know that,” but…

Suddenly, my sister’s voice became terrifyingly cold — like a completely different person. Her eyes held a color I had never seen before, and I lost my words.

Was that really her voice just now…? It lasted only a moment. Maybe I imagined it.

“…That’d be nice.”

“Yeah.”

I saw her usual lovely smile and hazel eyes. That put me at ease.

“Alright, let’s go to sleep. Together.”

“Yeah!”

Huh? Too cute. The best reply and angelic smile in history.

Yeah. I just need to hold onto this feeling.

She’s precious. I don’t want to dirty such a cute creature.

My sister is someone to cherish.

Even though she’s quite a troublesome sister…

“Good night.”