Hypotheses, Sleeping with My Sister
The handwriting was rushed, scrawled as if dashed off in a hurry.
Even the final sentence broke off unfinished.
It was a thoroughly unsettling scrap of writing.
My body and mind, still burning from the first kiss and caresses with Chaerin only moments before, cooled in an instant. The thin sheet of paper in my hand felt heavy as lead. The contents were far too loaded with meaning to dismiss as some random scrap that had simply gotten stuck inside.
This is no ordinary amnesia.
I must remember.
That meant the original owner of this body had expected to lose his memories. But a traffic accident was not something anyone could predict. I was caught up in some strange conspiracy—I was sure of it. A sinister premonition crawled down my spine: this might not be a simple possession into a gender-reversed world after all.
The moment the sound of Chaerin washing her hands in the bathroom stopped, I hastily stuffed the paper into my pocket. Then, until dinner, I searched every corner of the house while dodging her eyes. I found neither another memo of the same sort nor a single suspicious object.
Even seated across from her at the dinner table, the food would not go down. Chaerin asked if something was wrong, but I simply claimed I was tired. My mind tangled itself into knots of competing hypotheses.
First: intentional personality replacement. The possibility that the original owner, crushed by extreme stress or trauma, had wanted a new life and tried to swap his personality for “mine.” But the memo’s contents flatly contradicted that. “I must remember” meant he had never wanted amnesia. It could not have been something he chose.
Second: the subject of some secret experiment. The possibility that, without my knowledge, I had become a test subject of the government or some vast organization and had been deliberately injected with the memories of another “me.” Yet I could see no reason for such a thing. The original owner seemed to have been doing nothing more remarkable than ordinary male prostitution…
Third: a supernatural phenomenon. Straight possession. And the original owner had somehow realized it and left the memo. That, too, was possible. But how the original owner could have recognized possession and prepared countermeasures remained a mystery.
Fourth: virtual reality. The possibility that everything was part of an elaborately constructed simulation. Yet Chaerin’s body heat under my hands, the taste of food, even sexual pleasure—everything was far too vivid. The sense of reality was too overwhelming to believe it was all fake.
Last: multiple personalities. The possibility that extreme trauma had caused my brain to suppress past memories and identity, fabricating a new self called “the possessed me.” The memo could be a trace left by the suppressed original self. But this, too, felt wrong. My past-life memories were far too vast and precise—the reversed gender roles of society, an entirely different history and culture, even relations with other nations. My previous life was far too consistent and systematic to be a delusion spun by one traumatized mind.
Damn it. I don’t understand a single thing.
My head felt ready to burst. No hypothesis fit cleanly. Still, I could not help leaning toward the “possession” theory. My past-life memories were simply too detailed and clear—my name, the place I grew up, my trauma, the foods I used to eat. I could not believe those memories had been manufactured.
“Haa…”
A deep sigh escaped on its own. I wanted to believe my life was real, that this body was now mine. Above all, I refused to think of myself as fake.
“Hey, is something really going on with you?”
Chaerin, finished with the dishes, stood in front of me and asked with a worried face. I shook my head and said it was nothing.
In that moment I realized: perhaps even Chaerin standing right before me, or my childhood friend Subin living next door, might need to be treated with caution. I could not rule out the chance that the two people closest to me were involved in everything. Until I knew who had done this and for what purpose, I would have to watch myself. Sex, women—I might have to keep my distance for a while. I resolved to do exactly that.
But the resolve crumbled the instant I saw Chaerin’s back; my cock hardened at once. Fresh from housework, she wore loose gray slacks and a white short-sleeve T-shirt. To her they were simply comfortable clothes, yet the sight ignited my lust. The slacks hung loose, but every time she bent to organize the cabinet under the sink they clung to her ass and revealed its full shape. Through the thin fabric the white panty line showed clearly. I swallowed hard without meaning to. My cock swelled even larger. I used to stare whenever big-assed girls walked past dressed like that—yet here she was wearing the same thing at home.
I’m going crazy, seriously…
Honestly, I wanted to bury my cock between those plump cheeks. When Chaerin squatted and pushed her ass out a little, I reached full, painful erection. Thin waist, wide hips—the urge to take her from behind refused to leave my head. Those soft, full ass cheeks would act as perfect shock absorbers; the fucking would feel incredible. It was so arousing I half-believed she was deliberately seducing me. Now that I had tasted sex, my already vigorous desire only grew without limit. The thought of tsundere Chaerin, who usually snapped and nagged, moaning on my cock kept me rock-hard.
While reason and instinct waged war inside my skull, time flowed on indifferently. In the end, having solved nothing, I sat at the dining table and opened the diary I had brought earlier. The only thing I could do was hunt for more clues about this body’s past.
The diary began around age five. The crooked handwriting mostly recorded trivial daily life. One story appeared with striking frequency.
Today I went to the village gathering. The adults talked about boring things, and I played hide-and-seek with Jjokkom and Chaerin. I was it, but both hid so well that I searched for a long time.
Jjokkom?
A nickname I had never seen before. From context it clearly referred to a childhood friend. I guessed this “Jjokkom” was Subin’s nickname from those days. Most of the diary was filled with stories of playing with Jjokkom and Chaerin at that village gathering. The entries continued for roughly a year, then stopped cold.
While I turned the pages one by one, Chaerin finished the housework and came to stand beside me.
“Why are you reading that?”
“I thought I might recall some memories.”
At my answer her brows furrowed in a subtle frown—clear dislike.
Until recently I would have dismissed it as the cute jealousy of a tsundere desperate to devour her amnesiac twin brother. Now every flicker of expression looked suspicious. Did Chaerin not want me to regain my memories? Was she behind everything? Suspicions chained one after another until I barely managed to snap myself out of it. Before I knew it my gaze had locked onto the cleavage of Chaerin as she bent over the diary. The neckline of her pink apron and white T-shirt sagged with gravity, offering a perfect view of the valley between her breasts. I exhaled a deep sigh at my own uncontrollable lust.
“What’s this village gathering?”
I asked, forcibly dragging my eyes away. Chaerin frowned again.
“It’s like a cult.”
“A cult?”
“Yeah. Some weird religious group that tried to turn men into women’s slaves—brainwashing, magic, whatever it took.”
Her explanation hit like a blow. A cult that wanted to enslave men. Had they done something to me…?
“We thought it was just a normal village gathering. Before they showed their true colors, we moved here with Subin’s family. Lucky break, right?”
“What happened to that cult? Where are they now?”
“Last year, I think? News came out that the cult leader couple got caught trying to kidnap a man and were executed.”
Chaerin let out a genuine sigh of relief.
“If we hadn’t moved then, you might have been in danger too.”
I felt real concern for me in her voice, and my suspicion of Chaerin eased—just a little. I sorted the facts in my head. A cult that sought to make men into slaves. The leader couple executed last year. Had I been their final test subject? Had those cultists somehow caused the possession? Just as my thoughts began to tangle again, Chaerin’s gaze dropped to my lower body.
“…”
I looked down. My cock stood rigid, straining as if ready to tear through my pants. It had begun swelling the moment I saw her ass and had never subsided through the entire conversation. Chaerin’s face flushed scarlet. To hide the embarrassment she fell back on her usual sniping tone.
“Ahem. Ahem. My mattress got soaked earlier because of you… I don’t think I can sleep on it tonight.”
True enough—my caresses earlier had left the mattress wet with her juices.
“Oh. So?”
“…Can I sleep on the same mattress as you?”
The instant the words left her mouth, reason and instinct clashed inside my skull. Reason warned, Dangerous. Nothing is certain yet. Keep your distance. Instinct whispered, Yeah. Of course.
“Yeah. Of course.”
My mouth answered before I could even think. This was no battle between reason and instinct—just a total slaughter by instinct. Only after the words were out did I realize I had lost to lust again.
“Okay!”
Chaerin spun around with a bright smile. An ominous premonition settled over me: the feeling that I would not be able to control my desire.