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

Chapter 001: An Incident on a Summer Day

Checking the time on my smartphone, it was already past 9 PM.

Final exams were over, and it was Friday night right before a three-day weekend. To blow off all the built-up stress, six of us classmates headed straight to karaoke after school. Before long, friends from other schools joined in, and it turned into a loud party of ten people.

Even though it was free time, I was starting to get bored. Besides, I wasn’t that into singing anyway. —Oh crap, I forgot to message home.

“Well, I’m gonna head out soon.”

“Eh~ Teru, you’re going home already? Tomorrow’s a day off, just stay longer!”

“You’re such a buzzkill, Terumi! We’re pulling an all-nighter, right?!”

“Ehh, if Terumi’s going home, maybe I should head back too~”

I don’t have a curfew, and it’s not like I absolutely have to go home. It felt nice that everyone tried to stop me, and I was a bit reluctant to leave, but I had forgotten to tell my sister I wouldn’t need dinner.

“Sorry! Next time I’ll definitely stay till morning. See ya!”

Since these guys can be pretty persistent, I left enough money on the table to cover my share and basically fled the karaoke place.

Sighing, I hurried on my way home. Honestly, there was no real need to rush—or even to go home at all—but my sister was waiting alone, having made dinner for me.

This was extremely annoying. No matter how many times I told her to eat first, she would wait until I got home. Sometimes she even made food after I said I didn’t need any.

To be honest, I don’t understand what my sister is thinking at all. Our personalities are just too different.

When was the last time we actually had a proper conversation? Our communication is basically just me sending messages on LINE. And the only thing I ever send is “Don’t need dinner today.”

She just reads it without replying. Our chat history is nothing but my single message “Don’t need dinner today” repeated over and over at the top.

This can’t even be called communication.

When I opened the front door, my sister immediately came pattering down the stairs from the second floor.

Even though summer break was right around the corner, she was wearing her usual baggy, stuffy loungewear. Year-round, she always wears oversized sweat sets or hoodies regardless of the season.

She’s probably trying to hide her chubby figure, but seeing her like that in the middle of summer is a bit rough.

The fact that my sister, who is usually in the living room, came down from the second floor meant she had already taken a bath and was ready for bed. She could have just eaten by herself and gone to sleep. Or at least ask me if I’d be late.

“I’m home.”

“…”

She gave a small nod and headed straight to the kitchen. I went to the sink to wash my hands. I really wanted to jump straight into the bath, but making my hungry sister wait any longer would be cruel. I changed into loungewear in my room and then went to the dining table.

The savory, sweet-spicy aroma of braised pork filled the air. On the table were two servings of miso soup, white rice, and pickles. In the kitchen, my sister was reheating the side dishes.

She’s been cooking every day for many years, so her skills are basically professional level. She mostly makes home-style cooking, but sometimes she’ll serve something that makes me think “Wait, is this restaurant quality?” or “They sell this at the supermarket?” My mom would probably be offended, but I can barely remember what her real cooking tasted like anymore.

As I was thinking that, my sister carried over a large deep plate using oven mitts with mysterious animals on them. It was braised pork belly with daikon radish and boiled eggs. The rich aroma made my stomach, which had been expecting pizza and fries, growl loudly.

“Thanks for the meal.”

“…anks for the meal.”

I took a thick piece of braised pork onto a small plate and stuffed my mouth full. It was insanely delicious, as always. I’ve never had better braised pork even at restaurants. I shoveled down the rice—it paired perfectly. The miso soup was also ridiculously good.

While crunching on pickles, I glanced at my sister. She was daintily breaking the delicious-looking chunk of meat into tiny pieces and eating it very slowly.

I’m a fast eater, while my sister is the complete opposite—painfully slow. I feel pretty guilty that the person who made her wait finishes eating in seconds. Lately, that’s why eating together has started to feel a bit burdensome.

“It’s delicious.”

“……”

She nodded silently. As usual, the conversation didn’t continue.

I don’t know how many times I’ve said this, but I’ll say it again.

“I forgot to tell you I didn’t need dinner and came home late, so it’s my fault. But you don’t have to wait for me—go ahead and eat first next time.”

“……”

She put down her chopsticks and shook her head slowly while looking down.

“Sis, your food is really good, and I’m grateful you cook almost every day in place of Mom who’s always busy. But I have friends to hang out with too, you know.”

My sister stayed silent, head down. The corners of her plump lips drooped even further. Her curly bangs hid her eyes, and behind those unfashionable glasses, I couldn’t read what she was thinking at all. She was almost twenty years old, yet she couldn’t even make eye contact with her own family. I can barely remember what her eyes even look like anymore.

It started to irritate me.

“You don’t have to worry about me. You should go out to eat with your friends too. You get allowance, right? You’re a university student—why don’t you get a part-time job instead of staying home all the time?”

Seeing her start to tremble slightly while still looking down, I thought, Shit. I had gotten angry and taken it out on her.

“…Sorry. Thanks for the meal.”

Unable to stand the awkward atmosphere, I cleared the dishes and went to wash them.

I’m fully aware that I’m a scummy person. I’m quite self-centered, and I think I’m actually bad at maintaining relationships.

Even today, I didn’t come home early for my sister’s sake—I was just bored and decided to leave. Still, I manage to keep normal friendships without too much trouble.

But once relationships go beyond casual friendship, I sometimes get irritated over small things or suddenly feel everything is a hassle and want to reset everything without thinking about the other person.

Even so, I do try to be considerate toward my sister. When she looks sad like this, I can’t stand it, and thinking she must be lonely makes me come home early. Maybe it’s because the sibling relationship can’t be reset.

I feel stressed about myself for being like this, and lately I’ve also been building up some resentment toward my sister for making me feel this stress.

After finishing the dishes and looking back at the table, my sister still hadn’t moved, chopsticks resting on the table. It stung my chest. At the same time, anger welled up again.

This is how it always goes. Her signature sulking mode. She never says what she wants, just stays silent and looks down sadly.

She’s nearly an adult, yet she sulks like a little kid. I had nothing left to say, so I quickly retreated to my room.

Sigh. I flopped onto my bed and let out a deep breath.

Ever since our parents divorced, Mom got a job again at the big advertising agency she had quit and works late every day. She’s often away on business trips too. That’s probably why my sister feels lonely.

I have plenty of friends, and as for girlfriends… or rather, girls I have physical relationships with—I’ve rarely gone without one since around the second year of middle school.

But my sister is in university and I’ve never once seen a friend come over to our house, nor any sign that she goes out to play. I’ve never even seen her put on makeup and leave. She definitely doesn’t have a boyfriend. That said, she doesn’t seem like an anime or idol otaku either. Not that I’d know.

“She really doesn’t know anything…”

It’s strange how siblings can have such different personalities. But I don’t think her being gloomy and friendless has anything to do with the divorce. She was already like this before the divorce, right…? Hmm…? …Back then…

Ugh! Why am I even thinking so much about my sister? It’s gross. Time to take a bath and sleep.

I went down the stairs toward the bathroom. The living room light was off, so she must have already gone to bed. I felt a little relieved. If she had still been sitting there looking down, I wouldn’t have been able to ignore her.

I opened the door to the washroom. At the same moment, the bathroom door deeper inside opened.

My gaze was instantly drawn to the faintly flushed white naked body emerging from the steam. The first thing I saw was a tight, slender waist—then an unnaturally wide pelvis. Even from the front, I could tell how big her ass was from the shape of her hips, matched with thick, bursting thighs. Droplets of water ran down her long legs to her slender ankles. Above that mismatched waist was a mass of pure maternal femininity… Dangerous!

“S-sorry!”

I apologized quickly and slammed the door shut in a panic. Shit, how long was I staring? It felt like time had stopped.

Wait, who was that!? Was that my sister!? It should only be me and her in the house right now. But that body didn’t match the image of my sister in my head at all. She looked like a foreigner. Was her hair black? I can’t make sense of this.

My heart was pounding wildly. I tried to calm down.

Then the washroom door opened, and the familiar baggy pajamas rushed up the stairs at an unfamiliar speed. Water droplets flicked from her hair and wet footprints left the floor soaking wet.

“…Eh? Sis?”

I grabbed a towel from the washroom and started wiping the floor. I needed to move my hands or my head would go crazy.

That body was like something I’d only seen in American movies.

No… it was more arousing than any naked body I had ever seen.

The embodiment of seductive beauty burned into my retinas grabbed my heart and pumped blood straight down to my lower body.

That was my sister. It’s fine. I only got excited because I didn’t know who it was. I didn’t see her face. It’s fine. I’m not weird. I just didn’t realize it was her. It’s fine.

For now, I’ll cool my head in the bath. I stripped off my clothes, entered the bathroom, turned the shower lever to the coldest setting, and twisted the faucet.

“Cold!”

I gradually calmed down. On the other hand, it was good that it was my sister. If it had been a total stranger, it would have been way more awkward.

That was close. Thank goodness.

Still, I actually said “Sorry!” to my sister. That’s hilarious.

After getting out of the bath, I headed to the dining room to get a drink while brushing my teeth.

“……”

A tiny mosquito-like voice came from behind me. I turned around and saw my sister standing there fidgeting.

“Whoa! You scared me!”

“………”

“Huh? What?”

“…Thank you for wiping the floor.”

“Oh, no problem at all. You’ll catch a cold, so dry your hair properly before sleeping. Good night.”