The Difference Between Inside and Outside
“That crazy bastard… Our sister…”
Eun-su’s voice was low, but that only made it cut sharper through the air.
“Eun-su, no. Ha… haa… This is… really…”
Breath spilled from her lips before any words could form.
She had to say something. Anything. Right now.
She needed to deny it. Call it a misunderstanding, a mistake, offer some kind of explanation.
But the sentences forming in her head collided and tangled, refusing to line up into anything coherent.
“Are you even human? How could you do something like this… with our sister?!”
Eun-su’s ice-cold voice sliced across the room.
Gi-cheol couldn’t speak for a long moment. All he could do was drag in rough, ragged breaths.
“…Haa…”
A low, broken sound leaked from his throat.
His vision gradually sharpened.
Only then did reality settle into clear, merciless focus right before his eyes.
His wife, Eun-su, still held her phone pointed straight at him.
His gaze slid sideways.
There was Eun-jung—the woman who had just committed adultery with him. The one whose breath had mingled with his, whose body had been tangled with his only moments ago.
She had wanted it too. At least, that was what he had believed.
But now Eun-jung said nothing. She had retreated to the corner of the bed, wrapped the blanket tightly around herself, and wore an expression of pure terror.
She looked exactly like a woman who had been violated.
“Eun-su… I’m so sorry, sis. I really didn’t want it to come to this… I’m truly sorry.”
Her breathing was rapid and shallow, her words trembled, yet her face remained strangely composed.
It was the face of someone who had already wiped all emotion away once the deed was done.
Or perhaps… the face of someone who had been hiding her true feelings from the very beginning.
Gi-cheol’s eyebrows twitched faintly.
…This is wrong.
The heat that had filled the room just minutes ago had no connection to the scene in front of him now.
And the timing of Eun-su’s arrival had been too perfect.
Right at the moment of climax, when neither of them could have possibly cleaned up in time.
Eun-jung acting like she had been assaulted.
Everything aligned far too neatly.
It was too precise to be a coincidence.
Don’t tell me…
A chill raced down his spine.
Was this a trap?
The moment the thought crossed his mind, his heart sank like a stone.
But realizing it changed nothing.
He was already the worst kind of scum—an adulterer who had slept with his sister-in-law before the divorce was even finalized.
Anything he said now would only make things worse.
He hastily pulled away from Eun-jung.
While Eun-su continued hurling curses at him, he snatched the clothes scattered across the floor and threw them on.
Then he practically fled toward the door.
“You filthy piece of shit… You’re not even human!”
Eun-su’s final shout chased him from behind.
His hands wouldn’t stop shaking.
All he could do was get out of that house as fast as possible.
Only one thought echoed in his mind.
I’m finished.
***
Tae-seok leaned against the rooftop railing, slowly exhaling cigarette smoke.
The night air was cooler than he had expected.
It had been roughly five minutes since Eun-jung went inside.
He glanced at his watch, then fixed his gaze on the front gate below.
“I hope it doesn’t turn into an actual fight.”
He muttered the words as if to himself, but his expression wasn’t particularly tense.
He remembered what he had told Eun-su.
Don’t push too hard. The moment they’re caught is the most important. People become complete idiots then.
He had paused for a beat before adding,
Just let him run. There’s no need to chase him. That’s more than enough for us.
A small, tense smile slipped across Tae-seok’s lips.
“There shouldn’t be any other variables…”
He took another deep drag from the cigarette.
The smoke sank deep into his lungs before drifting out again in a long, slow stream.
If anything went wrong, he was ready to run down immediately.
After all, this plan had been his from the start.
And because they were his women, it was his job to protect them.
That was when he heard the front door burst open violently. A man came flying out like he was being chased.
His shirt buttons were only half done, his hair was a mess, and he could barely keep his balance as he staggered toward the parked car.
Without even glancing back, he sped off into the darkness.
Tae-seok watched the scene in silence for a moment.
Then,
“Pfft.”
A short laugh escaped him.
“Looks like it went exactly as planned.”
He pushed off the railing and straightened up.
The tension he had felt earlier had already vanished.
With his hands in his pockets, Tae-seok descended to the first floor with leisurely steps.
***
When Tae-seok opened the front door to Eun-jung’s house, the living room was empty.
Only half-drunk bottles and glasses sat abandoned on the sofa.
He stood there for a moment, breathing in the atmosphere, then walked slowly toward the bedroom.
He opened the door quietly.
Two women were embracing on the bed.
Eun-jung was the first he noticed.
She wore a disheveled dress, her face faintly flushed.
The heat of excitement still lingered in her eyes, and her shoulders trembled slightly—perhaps from lingering tension.
Beside her, Eun-su had her arms wrapped around her sister, gently patting her back.
Eun-su’s face was a complicated mixture of guilt, pity, and something deeper.
It was probably guilt and sympathy toward her sister, who had been forced into bed with her own husband because of Eun-su’s own troubles.
There would also be the shock of witnessing her husband’s infidelity firsthand after their short time together as a married couple.
If I hadn’t cheated on him with Do-hyun… my sister would never have had to do something so insane…
That self-reproach kept flashing through Eun-su’s mind.
Tae-seok stood there for a while, simply watching the two women.
The air in the room had not yet fully settled.
The sisters clung to each other, their breathing still slightly ragged.
It felt as though the events of just moments ago still lingered in the space.
Tae-seok walked forward slowly.
Eun-jung lifted her head at the sound of his footsteps.
“Tae-seok…”
At her words, Eun-su turned as well, a little late.
Her eyes were still swirling with unprocessed emotion, but ultimately they pointed in the same direction.
“Are you okay?”
He asked both of them.
Eun-jung nodded immediately.
Without hesitation.
She gently pulled herself from Eun-su’s embrace.
Then, naturally, she turned her gaze toward Tae-seok.
“Yeah… I’m fine. Just like you told me to… I pulled it off.”
Instead of answering, Tae-seok sat down on the edge of the bed.
He reached out casually and brushed Eun-jung’s hair back from her face.
His other hand took Eun-su’s.
“You got the evidence properly?”
He looked at Eun-su as he spoke.
“Yes… thanks to you…”
“Good job. This was all possible because of Eun-jung.”
His hand gently stroked her hair once more.
At that moment, Eun-jung’s breath trembled faintly.
This was exactly what she had wanted.
His praise. His acknowledgment.
The certainty that she was someone necessary to Tae-seok.
She slowly leaned her body toward him.
“Tae-seok… I…”
Her voice grew softer.
“…I did well, right?”
Like a child waiting for praise, Eun-jung looked up at him with slightly anxious eyes.
Tae-seok met her gaze.
Then he nodded.
“Yes. You did really well. Just like I said… it was easy, wasn’t it?”
The corners of Eun-jung’s mouth lifted slightly.
“Yeah…”
She let out a short breath and smiled.
“Just like you said, babe… he fell for it so easily.”
Tae-seok let out a soft chuckle.
“I told you there wouldn’t be a single man who could resist your seduction right now.”
Eun-jung averted her eyes for a moment before looking at him again.
“Am I… really that pretty? That attractive?”
“Haven’t you been feeling it lately? The way people look at you has completely changed.”
Eun-jung thought for a second, then shook her head.
“I don’t need other people’s gazes… The only thing that matters is how you see me.”
Tae-seok looked at her with affectionate eyes and said,
“You’re truly beautiful.”
Eun-jung’s expression brightened dramatically.
It was not the face of a woman who had just seduced and slept with another man—her own brother-in-law—on his orders.
No matter what she had done, one word of praise from Tae-seok seemed to wash it all away.
“Yeah… that’s enough for me.”
She smiled softly.
Watching the two of them from the side, Eun-su’s mind was swirling with conflicting thoughts.
Because of her, her sister had slept with her husband.
But it hadn’t been because of her request.
It had been on Tae-seok’s orders.
Just how deeply has sis fallen for Tae-seok?
The thought brought a wave of unease.
Will I end up like her too? No way… Me, sleeping with another man just because Tae-seok asked me to? I can’t even imagine it.
Goosebumps rose on her skin.
Yet…
Maybe she could.
The thought followed right behind.
Eun-su looked at Tae-seok’s face again.
This was the man who had turned her sister into this.
The man who had ordered her sister to sleep with her own husband and made it happen.
The man who had orchestrated this entire situation.
Who the hell are you, really?
He had dragged both sisters this deep, made them cross every forbidden line without hesitation, yet his expression never wavered.
There was no hesitation, no guilt, no sign of disturbance whatsoever.
Instead, he looked down at everything with the calm, almost leisurely gaze of someone who had seen it all before.
Eun-su’s eyes would not leave him.
That was when he spoke.
“Could you give us the room? I want to be alone with Eun-jung for a while…”
His voice was perfectly natural.
Eun-su’s eyes went blank for a moment.
“Huh? …Ah… yes… okay…”
She answered, but she wasn’t even sure the words had come from her own will.
It felt like her mouth had moved first and her body simply followed.
She rose slowly from the bed.
Eun-su stepped out of the room and closed the door behind her.
She stood right outside it.
Her feet refused to carry her any farther.
She could easily imagine what the two of them would do in there.
Tae-seok and Eun-jung.
Alone.
She knew all too well what kind of sounds would soon drift through the closed door.
She was supposed to leave.
She only needed to take one more step, but that single step would not come.
She slowly leaned her back against the door.
It felt as though a single door separated two completely different worlds.
Inside and outside.
The place where she could experience Tae-seok’s pleasure, and the place where she could only watch from afar.
Could I… accept everything Tae-seok asks of me, just like my sister?
The question circled endlessly in her mind.
Her sister did anything Tae-seok told her to.
And as a result… she was now receiving his body.
I’m jealous of sis.
A very faint sound came from beyond the door.
Eun-su’s ears perked up.
Then came her sister’s moan.
At first it leaked out low and long.
“……Mmm…”
Just that single syllable made the inside of Eun-su’s thighs tingle.
She unconsciously pressed her legs together.
Heat throbbed low in her belly.
The sounds from inside the room grew thicker, heavier.
Tae-seok’s low voice.
Her sister’s trembling breaths.
And the wet, obscene sound of flesh slapping against flesh…
Eun-su closed her eyes.
She pressed her back more firmly against the door.