Uhyeon walked the streets of Okcheon.
The village he was visiting for the first time in years was unchanged, as if time had stopped. The winding alleyways, the persimmon trees draped over the walls, and even the faint scent of earth brushing the tip of his nose.
Seoha had returned to Korea a few days ago.
Uhyeon felt the world shift around him at the sight of Seoha making his triumphant return beneath the public’s gaze and the media’s dazzling spotlight.
‘That tiny little kid, before I knew it…’
Seoha had grown splendidly, far beyond Uhyeon’s expectations. A faint smile spread across his lips.
‘No matter how I think about it, I was lucky.’
When he first came down to this rural village after receiving Yunmi’s urgent call, he had never imagined—not even for a moment—that he would meet such a child.
The sight of hundreds of scholars in an auditorium giving the boy a standing ovation. Having witnessed that wondrous moment directly, Uhyeon felt a choked, solemn emotion at the knowledge that he had stood at the starting point of that great journey.
‘Is this the place?’
His steps had stopped before the familiar house before he knew it. Boisterous laughter leaked out over the low wall.
“Mom! Are you going to plant pumpkins back there again?”
“That’s the plan. Your brother likes pumpkin leaves, doesn’t he? We’ll be able to eat them in the summer.”
“Huh? This is a doodle I made when I was little!”
A laugh escaped him.
Perhaps because time had passed, the atmosphere was completely different from the day of Seoha’s training center enlistment.
It was just a few weeks of basic military training, yet Seoha’s face had looked as grave as a soldier being deployed overseas.
Uhyeon couldn’t hold it in and burst out with a stifled laugh. To the eyes of Uhyeon, who had completed his service and been discharged as an Army sergeant, it simply looked like the cute whining of a nephew.
“Is anyone home!”
There was a commotion from inside, as if startled.
“Oh my, Teacher!”
Miyeong ran out cheerfully, wiping her wet hands on her apron. Perhaps because she had returned to her hometown, her face was full of life.
“What brings you here without any notice? The house is a mess because I’m unpacking right now….”
“I came because I have something to tell you.”
A table was set inside the room.
*Clack.*
When the instant coffee he was served every time he came was brought out, Uhyeon somehow felt his heart ease. Although her son had become famous and she herself had become a successful writer, this family hadn’t changed one bit. They clearly had enough means to buy an expensive mansion, yet the very fact that they insisted on keeping their old home was proof enough of that.
“Today, I came because of Seoeun.”
“Because of my daughter?”
Miyeong’s eyes went wide.
*Clatter-thud—*
A noisy racket came from beyond the door.
He had clearly heard voices outside, but Seoeun still refused to show her face. It seemed her cat-like habit of keeping her distance was still the same.
“Hoho! She’s just a bit shy around strangers.”
Miyeong laughed as if embarrassed, but Uhyeon’s expression was quite serious.
He carefully took out an envelope from his bag and placed it on the table. A letter of recommendation that could wield the most powerful force in Korea right now, at least where mathematics was concerned.
“Huh?”
Miyeong’s eyes shook.
It overlapped with the image of Uhyeon from over ten years ago, recommending early graduation to Seoha. She straightened her posture and shook her head with a serious face.
“Seoeun may be a bit smart like her brother, but she’s not a child who obsesses over nothing but math like Seoha.”
At her cautious reaction, Uhyeon nodded.
“Of course, Seoha was a very, very special child. Even at that young age, his identity as a mathematician was firm. But Mother, Seoeun is also not a child who can be contained within the bounds of ordinary.”
Miyeong was momentarily at a loss for words.
Because the image came to mind of her daughter, who had effortlessly surpassed even upper-grade gifted students while studying with the textbook Seoha made for her.
Uhyeon continued calmly.
“I have no intention of forcing this like I did with Seoha. It’s simply a shame that Seoeun’s numerical sense would be buried in mediocrity. How about letting her decide for herself?”
Miyeong thought for a moment, then looked toward the door and spoke in a low voice.
“Stop hiding and come in. We’re talking about you.”
A flinching feeling was sensed from outside. And a short while later.
*Squeak—*
Seoeun, now thirteen, walked in carefully without making a sound and sat down. Forty-five degrees behind her mother. It seemed she couldn’t feel at ease unless she hid her body to a suitable degree.
Having skipped grades in America, Seoeun had already graduated elementary school. From Uhyeon’s point of view, this was something he had tolerated for quite a long time.
“She plays actively when she’s at home, but she’s still a bit shy around strangers.”
“It’s not like that.”
Seoeun turned her head away coolly and spoke. She was still holding Justin, her friend, tightly in her arms.
“You should tell Teacher yourself.”
“Hmm? I don’t really have anything I want to say?”
“Oh my. Of course.”
Watching Seoeun roll her eyes and play dumb, Miyeong shook her head.
Unlike Seoha, her daughter was not the type to harbor fierce passion for something. She loved nature and animals, and had a hobby of collecting the medals her brother brought her.
Though she clearly had talent for mathematics, her disposition didn’t suit the atmosphere of a lone mathematician at all. Miyeong simply and humbly hoped her daughter would become a professional like a doctor or lawyer, or graduate from a prestigious university and get a good job.
Uhyeon spoke with a bright smile.
“As I said, I have no intention of forcing her. Not everyone who is good at math needs to become a mathematician. Seoha was an excessively special case. Because he possessed the virtue most necessary for a mathematician—patience and perseverance—from the very beginning.”
Miyeong laughed and waved her hand.
“Oh my, she has none of that. If she finds something uninteresting, she loses concentration immediately.”
Uhyeon stroked his chin and looked at Seoeun.
“Haven’t you been studying math steadily all this time?”
“That’s because I’ve been doing it with my brother since I was little. And he explains it in fun ways.”
Seoeun spoke as if sulking at her mother’s harsh criticism.
But there was also a reason she couldn’t bring herself to tell Uhyeon.
Her brother looked happy when he taught her math. Even while explaining a problem, at some point his eyes would light up, his gestures would grow bigger, and his words would quicken.
She hadn’t known it then, but the Seoeun of today knew. Her brother had been happy to share the world he discovered with someone. Seoeun wanted to continue sharing that with him.
“What are you learning from your brother these days?”
“Uh, um… Stream water?”
“What do you mean by that?”
Uhyeon tilted his head and asked. Seoeun quickly got up and brought the book her brother had made. *Mathematics a Special Assistant Should Know*, now in its third volume.
*Rustle.*
The cover looked just like a picture book.
Uhyeon turned the pages with a light heart. In the front were the geometric symmetries of a fluttery dress’s frills and the fractal structures of plant leaves. Following that, the principles of harmony and sequences using piano keys were explained charmingly.
A textbook that translated the forms of everyday objects into high-dimensional mathematical language instead of rigid symbols. Uhyeon inwardly marveled at Seoha’s insight.
‘Though it’s not a book just anyone can read.’
To his eyes, having authored countless textbooks as an instructor, this book was the most beautiful and adorable invitation written for only a single person in the world. Of course, the destination was needless to say the world of mathematics.
“Here, the stream! This is the most fun lately!”
A stream bank drawn with multicolored colored pencils.
Stream water splits when it meets rocks and speeds up when passing through narrow places. Water also has viscosity. Therefore, the water touching the bottom flows relatively slowly, and the water above has to expend energy to pull it along.
At the density of knowledge contained in this charming picture book, Uhyeon felt as if his breath had caught in his throat.
“Good heavens.”
Uhyeon felt a thrill. Not toward Seoeun, but toward Seoha.
This book was a guide designed to allow the still-young Seoeun to approach the highest levels of mathematics without any sense of rejection.
Watching the elementary-school-aged child mathematically explain the bright, flowing stream, Uhyeon completely forgot the purpose for which he had come here.
“May I see Seoeun’s room?”
“Okay!”
Had the sense of distance lessened somewhat? Seoeun readily got up and guided Uhyeon to her room.
The first thing visible on the desk was a three-compartment wooden medal case that seemed to have been made by her father. Its shape was similar to the watch storage case in his own home’s dressing room.
In the center spot, a golden Fields Medal glittered proudly.
“Why are there three compartments?”
Seoeun placed her hand on her waist and spoke boastfully.
“Math medals come in a set of three. Since my brother will bring them anyway, I asked Dad to make it ahead of time.”
The Big Three of mathematics prizes.
Seoeun’s medal collection was growing in scale. Of course, it was because Sujeong had been secretly egging her on.
“You don’t want to win them yourself?”
“Hmm…”
Seoeun fell into thought, placing her finger on her lips.
“Not really?”
The answer came with an untroubled smile.
It seemed Seoeun placed greater meaning on the fact that they were precious gifts from her brother rather than on the medals themselves.
“Then I’ll see you again next time.”
Uhyeon promised Miyeong that he would write a recommendation letter anytime she wished, and then exited through the front gate.
‘There’s no need to rush. I hear the gifted high school is already making moves.’
The gifted high school that had produced the greatest output named Yoo Seoha had become Korea’s most prestigious high school in just a few years. A school that countless gifted students across the nation sought out as their first choice.
Rumors had spread throughout academic circles that the principal there had his eyes on Seoeun.
*Rumble—*
Uhyeon got in the car and started the engine. However, he couldn’t readily drive away and looked outside as if something lingered. It was because the shock of the textbook he had seen earlier still hadn’t faded.
“Seoha. Just what did you want to teach your little sister?”
The truth was, he hadn’t had any particular intention.
Since his younger sister liked nature—rain, wind, and water—he had merely tried to explain it logically and simply. But to Uhyeon, a completely different landscape was visible. Because—
“That’s the Navier-Stokes equation.”
Strength entered his hand gripping the steering wheel.
The foundation of fluid mechanics and a problem among problems that modern mathematics showed no sign of conquering. If this were solved, humanity would advance to a new chapter. Because human control over nature and climate could dramatically increase.
The Neolithic Revolution, the Industrial Revolution, the Space Age, and now, to the world beyond.
“I’m probably overthinking.”
Uhyeon shook his head and cast aside his thoughts.
*Vroom—*
Driving along the national highway, he felt déjà vu. Streets and shops that looked familiar.
‘When have I been here before?’
Suddenly, a restaurant sign in the distance caught his eye.
[Okcheon’s Best Fish Noodle Soup]
Memories surfaced. It was the restaurant he had gone to on the day he first came to Okcheon.
Uhyeon parked the car in front of the restaurant as if entranced. It wasn’t because of longing for Yunmi. She had married a good man and built a happy family.
*Ding-a-ling.*
“Welcome!”
“One fish noodle soup, please.”
He sat by the window and waited a short while before a bowl of noodles was placed before him.
Steam rose above the red broth. Uhyeon picked up his chopsticks and stirred the noodles vigorously. Perhaps because of the fish dissolved into the broth, the consistency was thicker than expected.
The sharp scent of perilla leaves and Japanese prickly ash powder that had been added generously stimulated his nose. Suddenly, hunger washed over him.
*Slurp.*
“Huh?”
‘Why is this delicious?’
It definitely hadn’t been to his taste the first time.
The distinctive fishy taste of freshwater fish was absent. Instead, umami exploded in his mouth, and the noodles clung perfectly to his tongue.
Uhyeon sweated profusely and cleanly emptied the bowl of fish noodle soup.
* * *
“Training is combat! Individual combat!”
The recruits’ thunderous slogans echoed across the drill ground. The recruits training in the adjacent platoon had faces full of dirt, showing how much they had rolled around.
But for some reason, the platoon Seoha belonged to was an exception.
“Trainee No. 17, Yoo Seoha!”
His voice calling out his rank and name was solemn.
Seoha had never once considered receiving special treatment or exemptions. He had resolved to empty his mind and do his best as an Army trainee, at least for this moment, but…
“Virtual enemy spotted up ahead! Squad, advance slowly! Do not rush. Slowly!”
“Squad, slow advance!”
The moment the drill instructor’s command fell, Seoha sprang up like a spring and dashed toward the target.
At that moment, the company commander under the command post tent in the distance screamed and ran over.
“Stop! Stop right there!”
The company commander’s face turned pale, as if watching his own child jump into a burning building. He blocked Seoha’s path, gasping for breath with his lungs filled to the brim.
“Hah, hah… Trainee Yoo! Why are you working so hard? I told you to take it easy!”
Broad smiles bloomed on the faces of the trainee peers behind Seoha. Conversely, the officers and drill instructors were dying inside.
The drill ground was smooth without a single pebble, and soft dirt was laid on the ground to prevent injury from falling. A special order that had come down from none other than the Minister of National Defense.
They merely wished for this overly enthusiastic trainee to finish and leave as soon as possible.