Chapter 1 — Brother-in-Law... Don't Do This

This is a work of fiction. Names, characters, places and incidents are the product of the author's imagination. All characters are adults aged 18 or over.

---

I was 32 when I married my girlfriend of five years.

We'd broken up and reunited countless times over those years, and each time we found our way back to each other, it was thanks to my wife's older sister.

This is the story of the secret moments I shared with her older sister.

Her name is Claire Seo. She's 35 now, a Korean language teacher at a high school.

Despite her age, she has a youthful face and a voluptuous figure. Whether it's because she's picky or simply uninterested in men, she remains unmarried—an unmarried woman, as she jokingly calls herself.

She always claims to be a lifelong single, yet she keeps going on blind dates. And every time, she complains to me:

“Ugh, today's guy was such a middle-aged creep. Did you see his bald spot? So gross. What do they think I am? David, why am I so unlucky with men?”

It was a daily routine.

Honestly, even I thought she looked no older than thirty—some people even guessed she was in her mid-to-late twenties. She had that kind of ageless beauty.

But what drew my gaze most was her full, round breasts.

My wife was slim and petite-breasted, but her older sister had large, lush breasts—the kind that made any man want to reach out and touch them, just once.

Needless to say, she had no shortage of male attention. From twenty-year-old boys to forty-five-year-old married men, her suitors came in all shapes and types.

She was always kind to men who showed interest in her, but she never crossed the line.

That unattainable quality—someone you could almost have, but never quite—made her even more desirable.

Truthfully, I was no different.

I met her through my wife, and from the start, she'd been my confidante—someone I could talk to, someone who'd drink with me when things got rough.

Even after marriage, I still called her by her name.

As time passed, I found myself growing more attached to her than I ever had to my own fiancée.

Once, jokingly, I told her I liked her.

She laughed it off.

After that, I buried my feelings deep inside and married my wife.

After the wedding, my wife and I settled near Claire's apartment. Whenever my wife waited for me after work, she'd often spend time at Claire's place.

Today was no different.

I headed to Claire's apartment to pick up my wife.

Ding-dong… ding-dong…

“Who is it?”

Her voice was bright and sweet. Most women her age sounded matronly, but hers was still as pure and clear as a young girl's.

“It's me.”

“Oh! David! Wait a sec.”

A moment later, she opened the door with a warm smile.

I smiled back, but my heart was pounding.

She was wearing a plain white cotton nightdress, sleeveless and simple. And unless my eyes were deceiving me—she wasn't wearing a bra.

The small, dark nubs at the center of her full breasts were clearly visible. The thin cotton clung tightly to her curves, imprinting every detail onto my vision.

I forced myself to sound casual, pretending not to notice.

“Where's Emma?”

“She just left earlier. You should've called. Since you're here, why don't you come in and have a drink?”

“Sure. I'm thirsty. Got any juice?”

I slipped off my shoes and sat on the sofa in her living room.

As she walked toward the kitchen, her backside caught my eye again.

Her tight, round ass—no panty line in sight.

She was probably not wearing any underwear.

When she leaned over to pour juice into a glass, I instinctively straightened my back and lowered my eyes, stealing another glance at her full, swaying breasts.

It had become a habit.

She sat beside me, chattering about her day, her students, random things—laughing brightly.

But my nerves weren't tuned to her words. They were focused on the soft, warm weight of her breast, brushing against my arm each time she moved.

My cock was already fully erect. I hunched slightly to hide it.

“Oh! Right! I almost forgot—I was supposed to give this to Emma. Since you're here, just take it.”

She got up and headed to the kitchen.

She stood on her tiptoes, trying to reach a large pot on top of the fridge, grunting as her fingers slipped. The pot crashed to the floor.

“Oh no! Ugh, now I'm all wet…”

Coincidentally, the pot had been full of water. It soaked straight through her dress, right over her breasts.

I stared, wide-eyed, at her drenched chest.

Through the wet white cotton, her dark nipples were clearly visible.

As she wiped at her chest, her breasts swayed with each motion.

I couldn't hold back. I subtly placed my hand on top of her breast.

“Hey, clumsy. Be more careful. What's this? You're soaked. But why was there so much water in the pot?”

I rubbed her breast under the pretense of drying her off.

She flinched at my sudden touch, but didn't seem to realize my true intentions.

“Yeah, I'm such a mess. Anyway, take this to Emma. I was just about to shower.”

“Got it. I'll head out then. You get some rest.”

“Mm. Bye~”

She walked me to the door, waved, and closed it behind me.

Click.

I knew her habit—she never locked the top latch.

But I had a key. My wife had given it to me once, just in case something happened. Living alone, she said. For emergencies.

I had it in my pocket now.

I hesitated—should I go back in?

Then I decided: do or die.

Click.

The small sound echoed loudly in the quiet hallway. I tensed—had she heard?

But I twisted the doorknob anyway.

I stood by the shoe rack, watching the bedroom.

Claire was moving around inside. Still in that wet dress. A few moments later, she slipped it off.

Pale skin. Full, swaying breasts. And between her legs—dark, thick pubic hair, partially covering her slit.

My heart pounded like it would burst.

She walked naked into the bathroom.

I crouched by the shoe rack, struggling to calm my rock-hard cock.

Part of me wanted to burst into the bathroom, shove this hard thing right into her. But a sliver of reason held me back.

I left again, quietly locking the door behind me.

That night, my wife had an orgasm for the first time in a long while. She asked me, giggling, if something good had happened.

Good? Nothing. I just imagined my wife was Claire. That's all. But the thought had me so aroused, so satisfied.

It was Sunday morning. I'd just seen her naked. Barely a few hours had passed.

My wife told me she was visiting the countryside—suddenly missed her mom.

“Honey, I'll be back. Make sure you eat. If you're lazy, just ask Claire to cook for you. Okay?”

“Yeah, go. I'm not a kid.”

“Hehe… Feels like I'm leaving a baby behind. Anyway, I'll be back tomorrow afternoon. Mwah.”

She kissed my lips lightly before stepping into the elevator.

A dull, empty Sunday. I hadn't realized how much she filled the space—until she was gone.

I rented a movie, took a nap. Just killing time.

Ring… ring…

“David? It's Claire.”

Her voice—so welcome.

She said she was bored without Emma, so why not have a drink?

We met at a grill house near the apartment.

One bottle. Two. Claire was past her limit. She looked fine, but I knew her well. She usually couldn't finish one soju.

Tonight, she'd nearly downed two on her own.

I wasn't sober either. My head was hazy. Her tongue was thick, slurred.

After a while, I helped her, stumbling, back to her place.

“Naaaaah… Gaaah… Hohohoho… I wanna sleep with Davidii… Heehee… What should I dooo…”

“Yeah, yeah. You're heavy.”

“Hohohoho…”

She kept laughing. For some reason, she looked cuter, sexier than ever.

The thought made my chest tighten again.

She was drunk. I knew she'd pass out like this—sleep through the night.

What should I do?

I kept thinking as I led her to her room.

I sat her on the bed. She fell backward.

“Mmm… Brother-in-law… You came… So nice… When I go… lock the door… with the key… okay?”

“Got it. Sleep well.”

“Mmm… G'night…”

I said goodbye, opened the front door, then closed it without leaving.

I locked the latch, then returned to her bedroom door.

Earlier, I'd left it slightly ajar on purpose.

Now, I watched her through the crack.

She lay exactly as I'd left her—motionless.

I leaned against the wall by the door, waiting.

Over thirty minutes passed.

I stepped into her room.

She slept with such an innocent expression. So damn cute.

I sat on the bed, stared at her, then gently kissed her moist lips.

She didn't stir.

My blood rushed to my cock.

With trembling hands, I unbuttoned her shirt one by one.

Each button revealed more skin. My heart pounded harder.

Soon, her bra-covered breasts came into view.

The soft mounds above the fabric.

How many times had I dreamed of touching them?

I placed my shaking hand gently on her breast.

So soft. Warm. I could feel her steady breath.

I grabbed the bottom of her bra and pulled it up to her collarbones.

Her breasts were incredible.

Full, firm, perfect.

I cupped them gently with both hands, squeezing slowly. My palms filled with her warmth. Her flesh yielded under my touch.

I removed one hand and stared at her nipple.

Light brown. Slightly flattened from being confined in the bra.

I flicked my tongue against it lightly.

As my tongue traced over it, I felt it stiffen—slowly, then fully.

I took the hardened nipple into my mouth and sucked.

Slp… slp… slp… suck…

I pulled back sharply. Her breast lifted with my mouth, then jiggled back into place.

Her nipple was now fully erect—hard, swollen.

Her breathing had become slightly irregular.

She was asleep—but her body was awake.

I slid my hand under her skirt, touching her panties.

Thick mound. The slit between her legs—clear under my fingers.

I stroked the upper part of her slit with three fingers, while sucking and teasing her nipple and breast.

Her breasts were now dotted with red marks from my lips—so erotic.

My cock was throbbing, ready to burst.

Her breath grew heavier as I rubbed her harder.

I pulled her skirt up over her hips, then slid her panties down, tossing them aside.

Her dark, tangled pubic hair came into view.

I stroked it with my palm, then stripped off my pants and underwear.

My cock stood straight up—angry, desperate.

A drop of pre-cum glistened at the tip.

I spread her legs and stared at her pussy.

Her body was aroused—her slit glistened with wetness.

I used one finger to circle her clit, another to slide into her.

My finger slipped in easily, thanks to her slick arousal. The warmth, the softness, the slight roughness inside—everything sent shivers up my spine.

Her breathing grew ragged with each movement.

I pulled my finger out and brought my mouth to her pussy.

Slp… slp… slurp… slp… slp…

Ah… Mmm… Ah…

Finally, a moan escaped her lips.

My tongue was soaked in her juices. Her thighs and pussy were slick with my saliva.

When she moaned, I pushed my hard cock into her slippery slit.

Huh… Mmm…

Ah…

My cock filled her. She gasped.

I watched her face as I slowly thrust in and out.

Her expression twisted with arousal. Her arms, once limp, now wrapped around my neck—unconsciously pulling me closer.

How long had I dreamed of this?

Feeling her face, her arms—I thrust harder.

Thud… thud… thud… thud… pfft… pfft… pfft…

Ah… ah… ahh… ah… ah… ah…

Her grip on my neck tightened. My eyes locked onto her bouncing breasts as I moved faster.

Her moans climbed toward climax. My cock swelled, ready to explode.

Ah… ah… ah… hah… hah… Jeo… Jeobu… hah… hah… don’t… hah… hah… ah…

It happened so suddenly.

Her eyes were closed, but she moaned and spoke to me.

I froze—panicked, tense.

I stopped moving, leaving my cock deep inside her, and stared at her face.

She still had her eyes closed, breathing heavily.

“Haa… haa… Don't… Brother-in-law… Don't… If you do this… haa… it's wrong… haa… no matter how drunk I am… haa… we can't…”

“Claire. I've liked you for a long time. Every time I saw your breasts, I wanted to touch them. Every time I saw you, I wanted to fuck you.

I've been holding it back. I'm sorry I took you like this while you were drunk.

I know it's wrong. Cowardly. But I couldn't help it. When I see you, I get so turned on, so desperate… I couldn't stop myself. I'm sorry…”

I pulled my cock out of her and stood up.

Only then did she open her eyes.

Tears had formed in the corners.

“David. This… didn't happen. Okay? If Emma finds out… I can't face her. You know how much I love my sister.

And I love you too—my sister's husband. But this… this isn't right. I think you understand.

I must've been too drunk. I made a mistake. I'm sorry. Be careful going home.

This never happened. It's our secret. Understood?”

I nodded silently and left her apartment.

The next day, my wife returned, cheerful and bright.

Looking at her, I felt an unexpected wave of guilt and shame.

“Emma…”

“Hmm? Look at this. Isn't it pretty? It'll look good on you… Hmph…”

I kissed her lips—still holding my clothes—and threw her onto the bed.

I practically fucked her into unconsciousness.

She didn't resist. She let me take her again and again.

She climaxed. And I—experiencing the most intense, thrilling sex of my life—reached my peak.

Not because I was thinking of Claire.

But because of my wife—looking at me with loving eyes.