Blurring Boundaries
The sound of the simulator capsule door sealing shut felt like the only sound left in the world, wrapping itself around us in that instant.
The thin, skin-tight fabric clung to my body with no room to breathe.
A strange illusion of sweat already forming inside the suit came with a slow-building heat that rose from my chest.
And that heat was because of the person behind me.
No. It was definitely because of him.
Due to the cockpit’s design, I was bent forward, upper body pressed tight and prone, while Oppa positioned himself directly behind me.
A space so cramped our bodies were fused together.
A narrow gap that allowed no movement at all.
Inside it, even the faintest brush of his breath against the back of my head made my body react before my mind could catch up.
It should have been familiar after the first time, yet that familiarity only made me more sensitive.
The body heat that reached me even through the suit.
The maddening distance where he seemed one shift away from pressing fully against my lower back.
And his gaze that followed my every tiny movement in quiet obedience.
The brother who had stood beside me only moments ago was now overlapping me from behind, aligned with the center of my body. My head understood this was training, but my body refused to accept the excuse.
Every time I drew a breath and my waist rose and fell in the slightest rhythm, I could have sworn I felt his stare sliding down my spine. Or was that only my imagination?
I tried desperately to act unaffected until the activation tone finally sounded.
Quietly. And with agonizing slowness, the control yoke descended from the simulator’s ceiling.
When the metal frame connected to the feedback socket running along my spine, a soft click sent something sliding into my nervous system.
I flinched hard and clenched my teeth. Then Oppa spoke.
“Gripping the yoke now.”
“…Okay. Do it.”
The instant his hands closed around the controls, it felt as though his fingers were stroking somewhere deep inside me with relentless intent.
A foreign sensation of something being pushed in. Yet that intrusion melted into my breathing and heartbeat until it began to feel like my own.
Through the suit. Along the feedback lines. The sensation swept from my lower belly up beneath my heart and bloomed outward.
“Hngh…!”
My spine locked with electric heat. A scorching phantom touch near my backside shot up my vertebrae like lightning.
That reaction must have transmitted straight through the yoke, because Oppa turned to look at me, eyes steady. Asking without words if I was all right.
Under that gaze I muttered unconsciously.
“I really don’t think I’ll ever get used to this… It’s… hng…”
“What part exactly?”
I bit my lip, then slowly answered.
“…It feels different from when I do it with a girl.”
“How is it different?”
“Haa… haa… With a girl it’s equal. We give and take. The sensations leave me and enter her. There’s a natural flow… soft, gentle… hngh…”
I drew another shaky breath and continued, the corners of my mouth trembling.
“But with you, Oppa… it feels like I’m being overwhelmed. The sensations, my whole body… everything is being pulled toward you. Like my insides are being turned inside out and you’re forcing your way in with raw obsession… ah…”
The feelings pouring in through the coupling slowly pressed me open, crushing me with deliberate weight. Each breath turned into a moan whether I wanted it to or not.
That was why the words spilled out in such a mess.
Oppa stayed silent at first, as if he didn’t quite understand. Then he asked quietly.
“So you hate it? Coupling with me?”
I turned my head at that. My lips felt glued together. Something deep in my chest kept sparking painfully.
In the end I whispered.
“……I’m scared.”
My voice shook. The honesty of it startled even me.
“It feels like we’re touching places we should never reach… That’s why I hate it.”
There was one secret I had never told him.
Through coupling I didn’t only feel his sensations. I also caught fragments of his thoughts and emotions.
Of course the first time my consciousness had blurred from the high synchronization rate and I’d passed out, so I’d convinced myself it was just a dream or my own delusion.
But this was the second time. I knew for certain now.
It wasn’t imagination. It wasn’t a mistake.
Even now our minds were slowly bleeding together.
So this time I began cutting off my own thoughts and feelings, trying to keep them from reaching him. I turned the feedback into a one-way street.
I didn’t know the proper technique, but desperation guided my instincts and it happened naturally.
The boundary blurred. And then—
His thoughts and emotions began pouring in.
He said nothing. He didn’t have to. What he thought of me, what sensations he was drowning in; everything was painfully, shamefully clear.
There was nothing resembling normal sibling affection in any of it.
“Haa…. hng…”
Only thick, male instinct. The traces of desire he’d tried and failed to hide wrapped around me like chains.
I should have hated it. This was wrong between brother and sister.
Then why did my body keep reacting? Why was I being dragged deeper into his lust?
I couldn’t deny the emotions flowing from him.
“Mmm…”
At some point I found myself carefully adjusting my posture.
Leaning back into him. Shifting my hips and thighs, just a fraction, toward his body.
The shame burned my face when I realized I was deliberately moving to provoke him, but it wasn’t truly my will. It was the result of synchronizing with his desire.
At least, that was what I told myself.
This was only his emotions, his cravings being reflected through me.
Yes. Because in the end Oppa wanted this…
So I was simply giving it to him.
“Haa… haa…”
The more he focused, the higher the synchronization rate climbed, the hotter my body burned against my will and the faster my breathing became.
Just as an unknown heat consumed me and my entire body began to tremble—
The mechanical voice rang out.
At that cold tone my eyes flew open on instinct.
By the time my mind cleared, I felt Oppa release the yoke and slowly rise.
Had he noticed? I couldn’t tell.
I simply stayed there, dazed, breathing in soft, moan-like gasps.
Even after he stood, the afterglow of the coupling lingered throughout my body. A deep, lingering resonance that wouldn’t fade anytime soon. And the residual heat that had become mine alone.
When the simulator capsule finally opened, the first voice I heard was Kyoko’s.
“Whoa… Are these real-time numbers? How the hell did you two pull this off?”
Kyoko kept staring at the monitor in the control room, cycling through the frozen data again and again in open admiration.
“A synchronization rate of 80.4? What even is this…? I’ve never seen numbers like this during training…”
It was a figure impressive enough to shock even an expert.
Yet the two people who had actually been inside the simulator didn’t look happy. They simply stood in heavy, awkward silence.
Yuzuki exited the capsule first. She naturally created distance between herself and Yuuito, stepping aside as though even standing next to him made her self-conscious.
Her eyes were unfocused. Her breathing quiet.
She looked like someone who hadn’t fully returned to reality, standing there dazed, as if she had lost all sense of balance.
Beside her, Yuuito watched Yuzuki with a puzzled expression.
This coupling had been very different from the first.
To put it simply, the flow had been one-way, traveling only from Yuuito to Yuzuki.
For the first few minutes he had clearly felt her unique warmth and anxious tremors, but at some point the connection had been severed completely.
It wasn’t a natural fade. It felt as though Yuzuki had slammed a door shut inside herself, blocking the sensations with cold determination.
She had tried to hide it. Tried not to show it. And because of that, it had become even more obvious.
Which was why the instructor was marveling at a synchronization rate over 80, while to Yuuito it had felt shallower than the first time. Perhaps the actual rate had been lower.
…Does she still dislike me after all?
Yuzuki had shown clear signs of rejection even before they arrived at Dracore Academy. So this reaction wasn’t entirely unexpected.
Kyoko, observing the pair, raised an eyebrow.
“Hmm…? Why’s the mood so weird? You two didn’t fight in there, did you?”
Yuzuki flinched at the question. Focus finally returned to her eyes, as though she had only just remembered where she was.
She took a quiet breath, bit her lip, then slowly turned with a delicate smile.
“Aww… Why would I suddenly fight with my brother?”
Yet she didn’t step close to his side like before. Instead she kept a careful distance, tilting her shoulder, lifting the corners of her mouth as if conscious of the instructor’s gaze. Her voice rose half a tone higher than usual.
“We’re on great terms. Right, Oppa?”
The tone sounded like she was trying to paste over something.
Yuuito nodded slowly beside her, but his eyes remained puzzled.
His gaze asked why she was acting this way. A silent confusion lingered on her, searching for clues.
Yuzuki deliberately ignored it. That wasn’t important right now.
“Still… training does leave me a little tired afterward.”
Changing the subject smoothly, Yuzuki pressed a hand to her cheek and continued her flawless performance.
Her smile was the picture of a refined young lady. Polished speech, careful movements, nothing out of place.
Kyoko watched her for a long moment, then chuckled.
“All right, we’ll go with that.” She turned away.
Only then did Yuzuki let out a small, inward sigh. While her head still spun, she carefully glanced toward Yuuito.
She hesitated, reaching out to tug his sleeve, but withdrew her fingers at the last second.
She didn’t have the courage to call his name right now.