A Man Must Not Smile Carelessly
If there are people born with the memories of a past life, there would surely be those who envy them.
Someone like that could take the experiences and knowledge of their previous existence and build a life of growth and success, couldn't they?
Does a past life even exist? If it does, what kind of life did I live? If I could remember it, wouldn't it help me in this one?
I used to think things like that. More precisely, back in my first life on Earth, in the quiet moments I spent alone, watching the protagonists of the web novels I casually read as a hobby.
Looking back now, why the hell did I ever want that? The drawbacks clearly outweighed any benefits. I had no idea what kind of past life I'd even lived, yet I still entertained such stupid, idiotic thoughts.
Why?
Because…
It was the day of high school graduation.
I'd busted my ass studying in my own way and gotten into a pretty good university—not the absolute top tier, but solid enough. It was the final day of what had been a fun high school life, but the anticipation for college was so strong that I wanted to wrap things up happily despite the lingering regrets.
But then—
Shunk!
"Kyaaaaaah!!"
"Hyunwoo!!"
"Guh…!!"
Everything was chaos. What the hell just happened? Just a second ago I'd been laughing with the idiots I'd spent three years with.
And then—
"Y-You liar!"
"W-What on earth…"
Right in front of me, through my steadily reddening vision, stood a girl from my class who had just driven something heavy and solid into my body.
"You said you wanted to be with me!"
I couldn't understand a word she was saying.
Shunk!
"Guh!!"
All I could grasp was the searing pain and the simple fact that I was dying.
"Somebody stop her!"
"B-But she's got a knife!"
"T-Teacher—no, call the police!!"
No one around me came to help. They kept yelling for someone else to do something, but everyone was so panicked that not a single person even seemed to be making a call.
"Hyunwoo, you said you liked me… you said you liked me…"
Am I really going to die like this?
Shunk!
"Guh!! I never—"
Shunk!
"Liar! You said it would be nice if we went to the same school!"
Ah. Because we were classmates, and because my grades were good, I had once casually said it might be nice if we ended up at the same good university. But why would that—
"More than anything!"
Shunk!
I no longer had the strength left to scream. So this is really how I die.
"You smiled at me with that pretty face of yours!"
Shunk!
Fuck… so what, I was supposed to scowl instead?
Shunk!
"Th-That's not—"
I wanted to tell her that was complete bullshit, but—
Shunk! Shunk!
"Kyahahaha!!"
This crazy bitch never listened to the end. She just kept stabbing.
"If I can't have you, I'll destroy you!!"
Shunk! Shunk!
The kind of shitty line you'd only hear in a drama. That was the final memory of my first life.
But because I couldn't forget that miserable last memory, it carried over into the next life as well. Even now I still have nightmares about it.
I can only curse my past self for ever wishing I could remember a previous life.
You fucking idiot.
The moment I turned twenty, before I could even properly begin life as an adult, my first life ended. Taking that final lesson to heart, I made a decision.
No matter the situation—no matter how joyful or happy—I would never smile in front of a woman. Not even the smallest sound of laughter would escape me. I would not show so much as a light smile. Absolutely never.
Because in my past life, the face I had shown a girl out of simple goodwill, just to be kind—the thoughtless smile I had worn—might somehow work the same way in this life too.
And there was an even better reason this decision was the right one: the life I had been reborn into began in a world completely different from Earth, a place with an entirely different culture. Think of the fantasy worlds that appeared in the web novels I used to enjoy.
The problem was that the positions of men and women had been completely reversed.
A gender-reversed world.
I'll spare the detailed explanation. It's a little embarrassing to say myself, but in my first life my looks had been decent enough. That was probably what caused the ridiculous misunderstanding and led to that cruel, absurd end.
In this life, however, my appearance was absurdly beautiful.
Smiling with this face in a world like this? It would look like nothing less than an open invitation to every woman around. So as long as I lived, I would never smile at any woman.
Fortunately, the place I was born into was the northern grand ducal house of an empire known for its cold-blooded people. Not smiling actually suited the family, so no one complained.
Thus, in this life, I never smiled at any woman—not even the exclusive maid who had attended me since childhood, not even the knight who swore loyalty and always protected me, not even family: not my mother, not my older sister.
Perhaps the gods took pity on me for this, because I developed an instinctive ability to sense a woman's gaze. When I was little, a female assassin once snuck into the estate. I felt her presence and escaped the danger. The captured assassin turned out to be someone extremely famous in the underworld, yet I had instinctively seen through her stealth.
Thanks to that, I could detect the gazes of any women trying to look at me, so there was never any chance I would accidentally show them a smiling face. The sense was sharp enough to be called a superpower. For the sake of my survival in this life, I would never smile at any woman. Not even the lightest smile.
Lilith Freezid, eldest daughter of the empire's sole grand ducal house, found her little brother adorable again today.
No—how should she put it exactly?
Cute. Pretty. Beautiful. Like a living sculpture. That constantly prickly attitude of his was just too lovable!
Her younger brother, only a year her junior, had never once shown a smiling face in his entire life. More precisely, he had never shown one to any woman, including herself and their mother.
Was he just shy around the opposite sex? From what she heard from their father and the male servants of the house, he did smile around other men… and that made her jealous.
Surely his preferences didn't lean that way, right?
She had tried many times to catch him smiling in secret. Yet somehow—whether she was nearby or far away, whether she used a telescope, magic, or even stealth—she could never see her little brother's smiling face.
She had heard that in their childhood, the master of an assassin guild had infiltrated the Freezid estate to kidnap the siblings, and that her brother had noticed. She wasn't sure if the story was true, but her brother could sense a woman's gaze with uncanny precision. In the end, she had no choice but to give up on seeing him smile.
It was a real shame she couldn't see that smiling face, but it was all right. Because the sulky expression he had worn since childhood, the look of someone forcibly holding back a laugh—those alone were more than enough to make him adorable.
From the earliest moment she could remember, her little brother had remained unchanged, and that made him unbearably cute. Even without smiling or grinning, she could tell he was a kind and gentle person.
As the eldest daughter of the house, she had endured harsh education from a young age and often cried alone when it became too much. Every time, her little brother somehow knew exactly where she was and quietly stayed by her side. To a girl on the verge of breaking, that had been an enormous comfort.
And her brother was meticulous enough to always look after her whenever she got flustered and forgot something. That careful kindness of his was something she loved dearly.
Because he was there, she had been able to grow without major trouble as the eldest daughter who would inherit the Freezid house—as the next head of the family. At least, that was how she saw it.
That was why Lilith regarded her little brother not merely as family, but as a precious benefactor.
Whenever she spotted her adorable little brother, she never cared who was watching. She simply ran up and hugged him.
Whump.

"Ah! Sister, stop clinging to me!"
"Aww~ don't be like that, little brother~♡"
"I'm an adult now too, not just you!"
"We're family, so what's the problem~"
"As the next head of the house, maintain some dignity!"
"I don't need dignity when it comes to Ed~"
"Uwaaah! Just stop already!"
Today, as always, her little brother flushed with embarrassment at her behavior. He always snapped and got prickly, yet he never once truly rejected her. He always accepted it.
Today again, her little brother was so lovable—not only because of that extraordinarily pretty face, but because every single thing he did was just as cute.
"Haa… haa… I'm seriously exhausted…"
I really am exhausted. Because of the one and only older sister in this life, I end up worn out every single day.
I had never once smiled at her—not even a tiny smile—since we were kids, yet she was always so affectionate toward me. From what my friends back on Earth with older or younger sisters used to say, siblings usually fought like cats and dogs and couldn't stand each other. Maybe it was because I was born into a fantasy world.
From childhood she had never stopped throwing herself at me every single day, openly expressing her affection. When we were little it didn't matter. But the moment we hit adolescence, it became pure torture.
In this life I simply refuse to smile or grin at women so I can live without incident. That doesn't mean I'm a eunuch. I don't hate women themselves. But I can't exactly get turned on by my own blood sister, can I?
Day after day I had to endure the teasing she threw at me, and it was driving me insane. Around the time we became teenagers, her body had grown explosively. Was something like that even possible in reality? Her proportions were artistic—massive breasts and hips connected by a breathtaking body line. Any normal man would lose his mind just looking.
And that girl latched onto me every day? Even between siblings, it was an extremely difficult situation to endure. Just looking was already enough to make me crazy, and every time she hugged me and played around, the sensations I felt threatened to drive me completely over the edge.
I poured every ounce of willpower into not reacting. Because if I actually did react? I probably wouldn't die from a knife this time—I'd be torn apart under charges of incest.
So I could never become the kind of beast who reacted to his own sister. I was a rational person, the cold-blooded second son of the northern grand duke. No matter how beautiful she was, no matter how perfect her figure, no matter how much she clung to me with cute coquetry, I coldly pushed her away every single day.
Seeing her do this nonstop since childhood, part of me sometimes wondered if she was deliberately trying to kill me this way.
Anyway, as the cold-blooded second son of the northern grand duchy who never smiled—not even the smallest smile—I successfully endured another day.
In this life, at least, I will never die at the hands of crazy women for the absurd reason that I once smiled at them.
Never.
A man must not smile carelessly.